« $toneßroke Manor »

R. A. I. A. R.     DI & TWP Recharge
Instructions and Formula

The following document is a partially updated reprint of the original instruction manual as was enclosed in the DI & TWP Recharge Kit.
Included at the end of the reprint is a link to the simple household ingredients Formula for making your own Recharge Kit.

R. A. I. A. R.

Reef And Invert Aquarium Resources

Heritage Plaza, Suite 225, Publishing Office - Plaza Park Centre
12545 Olive Boulevard, 934 Valley Drive
St. Louis, MO 63141 Knoxville, TN 37920-4969

This is a reprint of the instruction manual enclosed with the DI & TWP Recharge Kit.
The Formula is now disclosed and offered as a FREE supplement to this document.
To Obtain the Formula, go to the agreement at the end of this document!

DI & TWP Recharge Kit


Dedicated to promoting money saving ideas and information to the aquarist.


This Instruction Manual and the Product Contents Label Information are protected by the copyright laws of the United States of America.    All rights reserved.

This manual, or any other documentation in this package, including product labels, may not be copied, translated, stored on electronic media or otherwise reproduced, nor can it be transmitted or forwarded on any electronic device, communications or otherwise, in whole are in part, without the prior written consent of Reef And Invert Aquarium Resources, Heritage Plaza, Suite 225, 12545 Olive Boulevard, St. Louis, MO  63141.  All rights reserved.  (Company Relocated!  New Address is RAIAR - Reef And Invert Aquarium Resources, Plaza Park Centre, 934 Valley Drive, Knoxville, TN  37920-4969




Read Carefully All Other Warnings and Directions on Each Label.

The Seller warrants these products for their intended use only.  Any misapplication or negligent use of these products will void any and all warranties-whether implied or expressed.  These products could become corrosive in nature as well as harmful to other items besides those designated in relation to the proper application.

Neither Reef And Invert Aquarium Resources, nor the seller shall be held responsible in any manner for any personal injury or personal property damage, or other type of loss resulting from the handling, storage or use of these materials.  The buyer assumes all risk and liability therefrom and accepts and uses these materials on these conditions.



Thank You for purchasing the DI & TWP Recharging Kit!
This Recharge Kit was designed to simplify the separation and recharging of mixed bed DI columns using Dow Chemical, Rohm & Haas, H.P., Sepratech, Miles, Beyer and Sybron resins.  These resins can easily be recognized by their exhausted cationic resin colors of Red, Blue, Deep Violet /Blue, Purple to Natural and Natural.  Note:  Miles & Beyer do not use color indication dyes in their resins.  Some color fade type resins do not regain their indicator color.

Within these pages you will discover a wealth of uses for your DI columns other than purifying your tap water for aquarium use.  In addition, various other uses for the empty cartridge housings are also included.

This recharge kit includes a sufficient amount of each chemical compound to enable the experienced hobbyist to recharge two standard size mixed bed resin DI units or one pair of separated bed DI columns.  If this is your first attempt at recharging mixed bed DI columns, and you did not achieve a good pre-separation of the resin layers, you may find it necessary to repeat the resin separation step using the remainder of your separation and recharging fluid.  To prevent this, practice the pre-separation step a few times, until you feel confident that the pre-separation cannot be improved.

A recharged mixed bed DI cylinder, in most cases, will remove contaminants for a longer period of time than the original unit as packaged by the manufacturer.  One explanation for this phenomenon is that the resin in the unit as shipped, was reduced in moisture content to the extent that a reduction in output or slight temporary damage to the resins adsorption ability may have resulted.  Neutralization of resins in mixed bed Ion Exchangers is another common factor.


TIP:  When operating a NEW AP TWP unit for the first time, it is wise to forcefully run DI water in reverse through the unit to wash excess carbon dust from the carbon pile in the bottom.  In rare cases, an excessive amount of dust size particles accumulate in the carbon bed and can readily clog the particle filter causing it to turn sideways under normal operation.  When this happens, the anionic resin is readily contaminated by the carbon particles turning it very dark.  Their is no indication that this harms the resin or reduces it's rechargeability.  However, it will stay darkened forever, making color indication hard to discern.

TIP:  Running two mixed bed DI columns back to back, improves the water quality of partially used DI units and allows you to run the first unit until completely exhausted before setting aside for recharge.  Tap water should be fed through the oldest unit first and then through the newer unit.  When you notice the newer unit has changed color for about 1/2 inch, it's time to move it to the first position and add a new or recharged unit to the second position.


Please read through the entire set of recharging instructions to familiarize yourself with the steps involved before attempting to use the chemicals included in this kit.
To assist in understanding the steps involved, we will use in our examples, the mixed bed DI column sold by Aquarium Pharmaceuticals, Inc. as the "Tap Water Purifier"(Tap Water Purifier is a Trademark of Aquarium Pharmaceuticals, Inc.)  DI columns sold or used with RO (Reverse Osmosis) units, although similar, usually do not include a carbon bed.


How to recharge mixed bed DI Columns for use as an Ion Exchanger for totally desalting water.

For clarity and safety, I will thoroughly explain each step in the order of operation, with comments concerning each step as applicable.  Immediately following the explanations, a condensed version, showing only the basic steps will be reiterated.

Additional equipment required (not included in kit)

NOTE:  Do not use the turkey baster in an attempt to remove the cationic resin (color indicating resin) from the column, it will clog the turkey baster.

The cationic resin will not be removed from the DI column; it's charging takes place within the column housing.



Please set aside 2 gallons of pre-filtered DI water or 1 gallon of pre-filtered DI water and 1 gallon of plain tap water for charged column flushing purposes.
Assemble the airline section to your turkey baster tip.  If the airline does not fit into the tip very snug, place a piece of rigid tube about 1/4 inch long into the airline tube end.  From the large end of the turkey baster, remove the rubber bulb and insert the airline tube into the baster housing and pull through from the tip end until it snugs firmly, then reinstall the bulb, note the grip ridge in the rubber bulb and get it seated properly.  The rigid piece of tube acts both as an expander and washer sealing the tube in the tip of the baster, a handy device to have around the aquaria at all times.

Protect your work area against chemical spills.  The kitchen or lavatory sink and counter will give you immediate access to running water should a personal hazard occur.  Remember, you are working with very harmful and dangerous chemicals.
Set up your waste retrieval bucket, anion charging cup, jugs of water, turkey baster and tube plug.  Keep a few disposable towels handy to wipe up spills and drips.


Before disconnecting your DI column from it's supply and carboy, or whatever arrangement you have set-up for it's use.  Has the mixed resin bed already partially separated or is it still firmly mixed?  In most cases, the bed has begun to partially separate, in the case of the AP TWP, it would have separated leaving the green resin at the bottom and the tan resin at the top.  The green resin is the cationic resin that turns dark blue/violet as it is exhausted.  If the resin has not already separated leaving the anionic resin at the top and the cationic at the bottom with only a small area of mixed resin in the center, please complete the following steps, it will save the amount of chemicals required for separation of the resins.

Note:  The volume of the resin decreases in use and most AP TWPs should show some signs of pre-separation.  Removing a little resin from tightly packed units helps speed up the pre-separation process.  All mixed bed columns will still retain a small mixed bed area between the tan and color changing resin due to neutralization of the resins from storage in their mixed bed state.  When the resins are fully recharged, they will again increase in volume, in some cases, all of the resin may not fit back into the cylinder.  You may save this resin for future replacement.

To partially separate your mixed bed DI column from it's set-up position.  Remove the outlet hose from the top of the DI unit.  Then holding the column, remove the cap by turning counterclockwise.  Remove the two foam filters from the top of the unit and set aside.  Using a Plastic spoon or your turkey baster, remove a small amount of the resin, less than 1/4 inch or about 2 tablespoons.  If using the turkey baster, first add DI water to the top of the column till full, then suck out the water and resin together.  Keep the removed resin, even if mixed, and place it directly into the anionic charging glass or beaker.  Replace the two foam filters.  Check the top rim and remove any resin granules that may prevent proper sealing.  Replace the cap and output hose.

Running the output to waste, turn on your water supply to the rate of about 2 cups per minute and watch the tan resin lift.  Then slowly decrease the water flow, a little at a time, in gradual steps, allowing the resin to separate.  You should be able to see clear water between the resins, as the water clears turn the flowrate down a little more.  It may take repeating this process of turning the water on and then decreasing the flow in steps several times to achieve a fairly good pre-separation of the resins.  Never turn the water on faster than two cups per minute, it could cause your particle filter situated between the carbon bed and cationic bed to turn sideways allowing carbon to contaminate the resins.

When the resins are fairly well separated, remove the outlet hose from the top of the unit.  Remove the inlet hose from it's source and connect the free end to the top of the unit, closing the unit from atmosphere.  This is the storage position!  The hose will be required during recharging as will a hose plug.  Newer AP TWP units come with caps over the barbs, these caps will not suffice as hose plugs.  In a pinch, you could use the cap from a ball-point pen, a wooden pencil, sharpened with the lead broke off, or even a peg from a light-bright toy.

The recharging process will include the following steps, do not perform the steps at this time.  Read through the process and what you should see happening during each step.  Commentary about each step and it's purpose including other options you may choose to utilize in your recharging operation will be included in this section.  Familiarize yourself with each step, even go through the motions if necessary, before performing the actual recharge operation.

Keeping the open end of the hose above the top of the DI column, remove the hose from the top barb and place the plug in the hose to prevent the unit from draining.  For safety reasons, allow the hose to rest in the waste bucket.

Remove the cap from the DI cylinder and set aside, upside down with the washer facing up.  Carefully remove the two foam filters from inside the column top and set in your previously removed top cap.  Initially these foam pads are white, if this is not your first recharge, the foam will most likely be stained yellow from the equalization process during the last recharge rinse.

Holding the hose outlet above the height of the cylinder, remove the hose plug.  Place your finger over the hose outlet and lower into the waste bucket.  Slowly release water from the column until the water level is below any mixed resin area that remains, but not more than about 1/2 inch below the top of the unmixed cationic (color changing) resin layer.  Again raise the hose above the height of the cylinder and replace the hose plug, for safety reasons, allow the hose to rest inside the waste bucket.  The reason for this step is twofold, first it prevents the anionic charging and separating fluid from further exhausting the cationic layer making charging more difficult and time consuming and secondly it allows you to use much less of your recharging and separating chemicals.

The next step, during the actual recharging process, is to add the anionic recharging and separating fluid to the cylinder filling it to within 1/4 inch of the top of the cylinder.  This being accomplished, carefully and gently stir the solution using your plastic or wood stir.  During this first stirring, you should be carefully reaching down into the mixed bed area of the resins, but not down into the cationic resin below.  Be very very careful, you are working with a corrosive and dangerous chemical that can cause blindness if splashed into the eyes.  Stir very carefully and slowly or you will dilute the separating and charging fluid beyond it's capabilities.  After a few minutes resting time, you should observe that the tan anionic resin has lifted to the top of the cylinder and the red or blue cationic resin has settled to the bottom, leaving a nice clear area between the two.  At this time you should pay special attention to the cationic resin layer and observe whether their remains any anionic resin near the top.  If so, carefully reach your stir down slightly into the cationic resin (below the clear area) stir very gently.

Note:  The separated anionic (tan) resin becomes partially gelled during this process and can cause the column to tip over when you begin to stir, so hold the cylinder firmly with your other hand.  You should also observe that the tan resin is beginning to darken to a deeper hue.

We are now going to remove the anionic resin from the cylinder using the turkey baster you prepared earlier, and place the resin in your glass beaker or measuring cup.  Your beaker may or may not already contain some mixed resin from a previous step, leave the mixed resin in the beaker.  Before performing this step, place your stir only partway into the anionic (tan) resin layer, gently stir to uncoagulate the resin and make it easier to remove.  Squeeze the bulb of the turkey baster above your beaker and then place the tip into the topmost anionic resin layer.  You will find that keeping the resin loose and in liquid motion makes this process much easier.  Removing this semi-gelled resin from the cylinder to the beaker is the hardest step in the whole recharging process.  Later, after charging and rinsing, you will find that the resin sinks and you can siphon the resin by first starting clear liquid up the siphon and then drawing resin in with the water.  As you add the resin and separation chemical to the beaker you will note that it continues to float and get gellous.  You will need to remove the separation fluid from under the resin, in the bottom of this beaker and place it back into the cylinder to keep a good separation area between the cationic and anionic resins remaining in the cylinder.  The airline you added to the baster will aid in your reaching through the resin to the separating fluid below and returning it to the cylinder.

When all of the anionic resin is removed from the cylinder and placed in the beaker, add more recharging and separating fluid to the beaker.  Use 1/2 of the bottle supplied in this kit, recap and save the other half for the next time you need to recharge your DI column.  Give the beaker a stir and allow the resin to rise, if any cationic resin sinks to the bottom, you should remove this using your baster and return it to the DI column for charging, If any liquid remains in the DI column above the cationic resin, remove this liquid with the baster and add to the beaker.  Stir the resin and recharging mixture that is in the beaker and set aside, out of the way, in a safe place.  A few granules of cationic resin left in the bottom of the beaker will not harm the anionic resin.

The next step is to rinse the separating fluid from the column.  This is accomplished by filling the column with water.  If you only set aside one bottle of DI water, use tap water for this purpose.  After filling the column with water, raise the hose above the cylinder and remove the hose plug.  Lower the hose draining the liquid into your waste bucket.  While the cylinder is draining, again fill with tap water and allow to drain completely.  When no more water drains from the unit, replace the hose plug and allow the hose to rest in the waste bucket.

If your DI column contains a carbon layer in the bottom section, (all AP TWP DI columns) fill this area with DI water from your previously filled container of DI water.  Do not overfill or fill past the filter disk between the carbon pile and cationic resin.  If you should get too much water in the column, you can drain it through the hose to your waste bucket.

We are now going to add 1/2 of the cationic recharge solution from the bottle included in the kit by pouring directly into the top of the cylinder.  Again be very very careful, the cationic recharge solution is a strong and dangerous acid, DO NOT INHALE above or near the top of the cylinder being recharged, the fumes are toxic.  Recap the cationic recharge solution bottle and put away.  You may notice that when you poured the acid into the resin that a yellow resin suddenly appeared from nowhere, this is not anionic resin you missed, I will explain it in a few moments.

Observe the filter disk separating the carbon from the cationic resin, is it horizontal or has it become tilted?  If it is even slightly tilted, using your stir and pressing the high edges, try to work it down so that it is again level and perfectly horizontal.  Don't worry if some of the cationic resin has managed it's way into the carbon.  Once you are sure the filter disk is level, lift your stir about 1/4 to 1/2 half inch above the disk and gently stir the resin for about 15 seconds.  If you are recharging an AP TWP DI column, you may notice the resin begin to return to it's greenish state immediately, or in some cases turn completely bright yellow.  Do not be alarmed, your resin was not completely exhausted.  Normally, during recharging, the resin will change from red or blue back to it's normal color state or lighter, over a the next hour.

Note:  If this is not the first time you are recharging your unit, or you obtained your recharging chemicals locally and your cationic resin turns clear or yellow, your home-brew recharge solution may be too strong and needs to be diluted for future recharging.  Have no fear, after rinsing, the indicating color will normally return to the resin, however, in the future, try not to subject your resins to overly strong recharge solutions.  A milder solution over a long charging period is more effective and longer lasting than a strong solution for a shorter period of time.

After you have stirred the cationic resin for about 15 seconds, rinse your stir in the waste bucket and restir the anionic resin in the beaker for about 15 seconds.  Again rinse your stir in the waste bucket.  Over the next hour, you will repeat this process four times 15 minutes apart.  Stir the resin in the column first, rinse stir in waste bucket, stir the resin in the beaker and rinse stir in waste bucket.

Now is a good time to replace your chemical bottles back in the box and wipe up any drips that may have occurred.  Rinse your Turkey Baster by drawing water out of the waste bucket and squirting it back in.  Take the column cap and two foam filters previously removed and wash them at your sink, so they are ready to replace on the unit after recharging.  While the unit is resting between stirrings, some of the acid is diluting with the water in the carbon chamber and beginning to purify and recharge that section as well.  Once we proceed with the recharging and rinsing process, the spent chemicals, which are still highly dangerous will be drained into your waste bucket.  From that point on, consider your waste bucket as very dangerous and take the same precautions as you do with the concentrated chemicals.  DO NOT empty your waste bucket!  The recharge chemicals are designed to combine in the waste bucket and neutralize themselves, rendering them safe for disposal into a sewer or septic system.  The environmentally conscious aquarist will test this waste water before disposal to assure a pH of 7.0 by using standard aquarium chemicals for adjustment before dispensing down the drain.

One hour has passed, you have stirred the resins for 15 seconds once every 15 minutes and are ready to proceed.  The first step is to allow the remaining acid in the cationic resin area to enter into the carbon area on AP TWP units.  This is accomplished by raising your hose above the height of the cylinder and removing the hose plug, then carefully lower the hose into the waste bucket, allowing the partially acidic water to exit the unit.  Be very careful, the effluent from the hose will soon be followed by the strong acid recharging solution as it drains from the cationic area through the carbon bed and into the waste bucket.

Now pour your jug of water into the top of the column, allowing it to run through the resin, through the carbon then to waste, rinsing the resin and carbon.  Tap water is OK but does reduce the life of the column after recharge slightly.  If you initially saved two containers of DI water, use DI water, but, do not use DI water if you only saved one jug full.  DI water is required for rinsing the anionic resin that is still recharging in your beaker.  Use an entire gallon of water, pouring into the top of the column and allowing it to drain through the cationic resin, through the carbon and into the waste bucket.  You may have noticed that when you first started adding the water to rinse the column that some black carbon was released into the waste bucket.  This is normal!  What has occurred is that the acid has re-etched new pores into the carbon pellets as well as cleaned out the existing ones.  Depending on your water supply, some impurities that were originally adsorbed by the carbon as well as impurities in the carbon itself, may show traces of red or orange deposits on your carbon, this too is normal.  After about 15 or 20 recharges, or when your carbon appears to have more than 50% impurities remaining after recharge, plan on replacing the carbon pile before your next recharge process.

Once your jug is empty and the column has completed draining, place the plug back into the hose.  Be careful that you do not splash any water from the waste bucket on you, your clothing, etc.  Then from your jug of DI water, add enough water to the column to cover the recharged cationic resin.  During the rinsing process you will notice that the original indicator color has returned to your resin, even if it turned bright yellow during the recharging process.  If you were using tap water for rinse water, you may notice that a few grains of resin near the top may have returned to the exhausted state, this is due to it removing pollutants from your tap water, just what it's supposed to do.  Some of you may notice that the resin color appears darker than it did originally, this is true in the sense that the resin was formerly mixed and the lighter color resin made it appear lighter, or in some cases, if your original column was in a fairly dry state when you purchased it, it may not have had a full life cycle charge left in the resin.

We will now rinse the anionic resin while in remains in the beaker.  DO NOT pour the resin into the column at this time for any reason.  I know it would be much easier to just pour the resin in and hook the unit up and run to waste to rinse the anionic resin.  However, in thus doing, you will destroy the cationic resin recharge almost instantly.  You will need your turkey baster assembly, jug of DI water and waste bucket.

Stir the resin one last time and allow it to float to the top.  Now using your baster, squeeze the bulb and then push the airline tube through the resin into the clear area below and wait just a second before slowly releasing the bulb to draw the liquid into the baster.  This liquid is very caustic, be extremely careful, empty the baster into the waste bucket.  Repeat if necessary to remove as much of the liquid as possible without wasting your resin.  Make sure you put all waste in the bucket to neutralize the waste water.

Fill your beaker with DI water and stir the resin, this time the resin should sink to the bottom, after a short period of time.  You can either pour off the water into the waste bucket or use your baster.  Keep repeating this process of adding DI water, stirring and moving the water to waste until your jug is empty and the beaker is still full of DI water.  By keeping the liquid that is left in your beaker the last rinse, it will be useful in transferring the resin back to the column.

You can initially pour some of the resin from your beaker slowly into the column, try not to upset the cationic resin at this time.  When the cylinder is full of water, allow the anionic resin to settle, using your baster remove the excess water and return it to your beaker.  You may want to try the pouring method a couple of more times, or until the column gets too full to use that method.  Again, remove the water from the top of the column with your baster and place it in the beaker.  Now hold the beaker at an angle and let the resin settle, using your baster suck up resin and transfer it to the column until the column is full to within 1/4 inch below the top or the beaker is empty.  Tapping the side of the DI cylinder will help the resin to settle.  Note:  The resin volume increases during recharging, If you have resin left over, you may save it for future recharging use.

Once the beaker is empty of resin, add some water to your column until it is almost overflowing.  This is so your foam filter pads will float rather than drop down on top of the resin.  Now carefully replace the first foam pad into the cylinder, followed by the second foam filter.  Check the top of the column to make sure no resin grains will keep the sealing gasket from seating properly.  Place the gasket, if removed during washing back into the cap and seat firmly, now replace the cap and hand tighten.  Holding the hose above the top of the unit, remove the hose plug and affix the hose to the top barb.

NOTE:  The unit is NOT ready for use yet.  Equalization rinsing will be the next step in the recharging process.  The unit should not be stored until after this process has been completed or the cationic resin may suffer damage.

Well, we are now at the easiest part of the recharging process, hook-up and drain to waste.  This is a very important step!  Do Not Omit this step.  Keeping the hose above the top of the cylinder, remove the hose from the top hose barb and affix to a water supply as you would for normal use.  DO NOT allow any water to drain from this hose.  Affix your regular output hose to the top barb and run to waste.  An alternative would be to invert the column over the waste bucket or drain and run a minimum of one gallon of tap water through the column.  Remove the outlet hose from the top of the unit, disconnect the inlet hose from your supply and connect it to the barb on top of the unit It is now ready for storage and in the storage position.  Before initial use for water purification, run a minimum of one additional gallon through the unit to waste before putting into service.

Carefully dispose of your waste water and rinse the bucket.  If you followed all the instructions and both chemicals were drained into the waste bucket along with the rinse water, the pH should be neutral and safe for disposal into a sewer or septic system.  You can use an aquarium test kit and standard aquarium chemicals to adjust the waste water to a pH of 7.0 if required.

If you wish to test your new DI column water pH before use, do not rely on the test to be anywhere near accurate, the effluent from a DI column cannot be properly tested.  However, it is not unusual for the effluent to read between 7.0 and 8.5 or even higher and lower than 6.0 after a resting period of several hours, using common aquarium pH test kits.  If you have a meter, the effluent should read between .05 and .06 microseimens.

What to expect from your newly recharged DI column or columns or the AP TWP!

The first  thing you have probably noticed is that we have not included in our directions a way of remixing the resin beds.  This was not an oversight, all DI columns operate more efficiently and last longer in the separated state.  In fact, if you own several of the disposable AP TWP columns, you may elect to place all the carbon in one column, the cationic resin in another and the anionic in the third column to facilitate easy future recharges without disassembly.  If you are running only one column or even two columns back to back, which is what I recommend, you will notice that recharged units last appreciably longer than original units.  This is due primarily because the units are fairly dry when shipped and the resins are mixed, this tends to allow the resins that touch each other to partially neutralize themselves.  You will also notice that unlike your spent new mixed bed DI columns, that you do not get the small mixed bed area in the column, the division between the cationic resin and the anionic resin remains sharp and well defined.  This is also due to the fact that you have no neutralization of resin from long contact in storage.  In addition, now that your resin beds are separated, you will be able to recharge your DI columns using supplies available locally and still obtain perfect separation for many recharges.

Sorry, we will not disclose our proprietary formulas for separating and recharging mixed bed DI columns.  The chemical solutions used for recharging are clearly noted on their respective bottles in the kit and could be obtained full strength from your local chemical supply house.  However, In the interest of safety, we have formulated the proper dilutions of each chemical and set the cost of the recharge kit below the actual retail price of the chemicals, in an effort to prevent the mixing, storage and disposal of very strong and hazardous chemicals by fellow aquarists.


For Reference Only, after reading the complete step by step instructions above.


In their separated states, wherein the cationic resin is held in an individual column and the anionic resin is held in a separate individual column, they can be utilized for various purposes around the home, freshwater, marine and reef aquaria.  Three AP TWP mixed bed DI columns may be separated into individual columns containing carbon in one, cationic resin in the second and anionic resin in the third.  Two RO/DI mixed bed columns may be separated into two separate stand alone cartridges with the cationic resin in one and the anionic resin in the other.


Water Softening:  A cylinder containing only the separated cationic resin (this is the color changing resin) may be regenerated using common table salt for use as a water softener.  When used as a water softener the resin does not change colors to indicate that it is exhausted and requires recharging.  The unit is exhausted when the degree of hardness begins to increase and can be tested with simple surfactant type home test kits.

Recharging is accomplished by thoroughly rinsing the column with tap water and then filling the column with a salt water mixture containing 7 ounces of table salt dissolved in a 2-liter soda bottle.  Stir or drain and refill once every 15 minutes for 1 full hour, then rinse with tap water until the output does not taste salty and return to service.

NOTE:  In softened water the hardness salts have been exchanged into non-hardness salts.  The osmotic pressure, conductivity and mineral content remains unchanged.  Plants are affected negatively due to the salt exchange.

Partially Desalting:  After recharging the cationic resin in it's normal manner as an Ion Exchanger, this cylinder may be used as a stand alone unit, to produce partially desalted highly acidic water.  The color changing resin will function normally indicating when the column is exhausted and requires recharging.  An excellent way to eliminate carbonate hardness from your supply.  The carbonates are converted into carbonic acid, which may be outgassed by aeration, other salts contained in the water are also converted into their corresponding acids rendering the water too acidic for immediate use.  Effluent should be aerated until a pH of 6.5 is obtained before use in your Amazonian aquaria.


Your DI column may be used on occasion, for short periods of time, to partially demineralize the water in your aquarium, thus reducing nitrates while increasing the carbon dioxide level causing flourishing growth of your aquatic plants.  Care should be taken not to reduce the total salt content of the aquarium by too much.  Keep an eye on your pH and use a hardness test kit.

If you are new to using DI columns to demineralize aquarium water, we recommended usage of your DI column for partial demineralization of your freshwater aquaria, which should be for purifying no more than 5% of the volume of your aquarium water per 72 hours or not to exceed three times per week.  Your DI columns may be installed inline with a bypass to allow the normal circulation flow of your pump to your aquarium and only a small sampling of water is passed through the DI columns.  Output should be measured carefully until you know the proper setting and time length required to achieve proper flow rate for 5% of aquarium volume.

The effluent of DI columns used in this way are very carbonate rich and should only be attempted by experienced aquarists if periods extending beyond a few minutes each day will be utilized.  The aquarium should be well aerated at all times to reduce excessive carbonic acid before it can rise to dangerous levels.

When recharging DI columns used for aquarium filtration, you will notice that the normally clear area between the resins during the separation phase will become cloudy or in some cases this same cloudiness may occur in areas of extremely hard water from normal usage.

See also, Partially desalting, above.  The desalting of water from your Amazonian aquaria can help maintain a more suitable environment for your various fish and plant species.  Partial desalting is not usually performed as an inline function.  Highly filtered water taken from your Amazonian aquarium, after passing through the cationic resin, is released into a catch basin where the water is thoroughly aerated before reintroduction to the tank.

NOTE:  The partial desalting of aquarium water, using only the cationic resin column, does not remove anionic chemicals from your aquaria, such anions include Nitrate and Phosphate.


Saltwater Purification:  The separated and normally recharged, as an Ion Exchanger, anionic resin column, may be converted into a very highly efficient adsorber by effectually neutralizing the charged resin for this adaption to purify marine and reef aquaria saltwater.

To neutralize the previously recharged, as an Ion Exchanger, anionic resin, for saltwater purification.  Dilute the supplied cationic resin recharging fluid by 50% with DI water in a separate container.  This is broken down as, 6 ounces of the cationic resin recharging fluid is to be mixed with 6 ounces of water purified through an operational DI column, in a separate acid safe container.  The drained anionic resin column is to be filled with this dilute solution of cationic recharging fluid and stirred or drained and repeated once every 15 minutes for one full hour.  The column is then to be thoroughly rinsed using at least 3 gallons of tap or DI water.

The use of the anionic resin, charged in the manner so indicated for the purification of saltwater, is usually performed as an inline unit and part of the aquarium circulatory system.  This is accomplished by placing the column in-line with a bypass to allow normal water circulation with only a sampling of the aquarium water being passed through the anionic resin at a flowrate not to exceed 25 gallons per hour.  Common practice is to flow only 5 gallons per hour through the unit.

pH buffering of Saltwater:  The separate anionic resin column may be charged in a manner useful for maintaining a stable pH in your saltwater aquarium.  The specially charged anionic resin column is placed in-line in the circulation system of your aquarium using the bypass technique explained above.  Recharging for this use requires several careful steps and none can be omitted.

Dissolve 4 ounces of Sodium Bicarbonate in 1 to 1-1/2 quarts of water in a glass or heatproof container and bring the water to a full rolling boil for 5 full minutes, on stove or in microwave oven, then add icecubes to make 2 quarts and assist cooling of the liquid to room temperature.  The normal white residue left on the container above the water line washes clean with plain tap water.

Charge the unit for one full hour using this solution, stirring once every 15 minutes or draining and refilling the anionic column on a similar schedule.  Do Not rinse with tap water, rinsing of the anionic resin column is to be accomplished by flowing partially desalted water from a properly charged cationic resin column only, through it until a pH between 5.5 and 6.5 is obtained.

To make the buffering generator solution, in 2 gallons of tap water dissolve 10 ounces of common table salt.  Once dissolved, begin adding drop by drop, the solution designed for normal recharging of the anionic resin, included in kit, until the desired pH of 8.2 or 8.3 is obtained.  This 2 gallons of solution is flowed slowly through the anionic column to waste until consumed.

The anionic column now converted for pH buffering may be connected in-line with your aquarium circulatory system as explained above.  Under normal conditions, the unit will maintain your pH at the constant level selected, 8.2 or 8.3, for up to 1 full month on aquaria under 150 gallons.


The spent cartridges from your AP TWP unit may be adopted for various uses around your aquarium, with and without the nice stand supplied with the original unit.  Although you can readily purchase hose barbs of various sizes from your local plumbing outlet to utilize the caps supplied with replacement cartridges for building the chemical reactors, the time and labor saved by purchasing complete AP TWP units, and the versatility they add, makes the additional expense worthwhile for in-line reactors and filters.  Even more so, now that you have the ability to recharge your columns for a fraction of the cost of replacement cartridges.

I strongly recommend to all users of the AP TWP DI units, to purchase four or five complete TWP systems from Aquarium Pharmaceuticals, Inc. to construct a state-of-the-art tap water pre-filter system that cannot be excelled by even the highest priced RO/DI units available.  The AP TWP filtration system, when combined with Poly-Bio-Marine, Inc.'s Poly-Disc PMA-1 Fin'l-Filter, placed ahead of the TWP DI column, shows a marked increase in the output capabilities of the TWP unit and greatly improves the water quality produced through the molecular absorption capabilities of the Poly-Disks.  Poly-Bio-Marine, Inc. also offers a PSM-1 unit filtering into the submicronic range.  Using their 0.20 micro (absolute) it is possible to Cold Sterilize water.

Through use, you are already aware that the AP TWP filter alone does an excellent job of cleaning up the water.  However, if you live in one of the numerous hard water areas, you were probably a little dismayed with the quantity of water, in some cases less than 25 gallons, obtainable from a single cartridge.  Even with low-cost recharge capabilities, an extended time between recharges would be a definite benefit especially in time savings.

Once separated, most users of the recharge kit combine the carbon and resins from three separate units into a single column for each component, which facilitates fast and easy future recharging of the columns without the need to re-separate the resins each time or even disassemble the units.  Many of these users have, in addition, placed a molecular absorption reactor (construction plans below) between the carbon column and the cationic column, further lengthening the time between re-charges.  A select few have maintained an additional mixed bed column as the fifth and final unit in their system to insure complete exhaustion of their separated columns before finding it necessary to recharge.

An enhanced water filtration system, over the AP TWP alone, would include the PMA-1 Fin'l-Filter or the molecular absorption reactor, immediately preceding the AP TWP filter.  An improvement over this system would include the addition of a second AP TWP mixed bed following the first mixed bed unit to assure complete exhaustion of the first filter before removal for recharge.  In practice, you would then move the existing filter to the location of the first and add a new filter at the end of the line.

A typical 4 column system would consist of a salvaged, empty, TWP cylinder that has been refilled with re-activated carbon from spent AP TWP filters and placed first in line.  The next column would consist of a molecular absorption reactor, also built from a salvaged cylinder.  The third column would consist solely of recharged cationic resin from three spent TWP units and the final column would hold the recharged anionic resin.  The only improvement to the 4 column system would be to add a mixed bed column so that you could run the separated bed columns until completely exhausted before recharging, as would be indicated by the cationic resin in the fifth mixed bed column beginning to show color change.


Reactor Components:  Not all of the reactors shown will use the components in this list.  I placed the component list first in this series to prevent reiteration and description of each component in each reactor's assembly instructions.  The components will be listed by a key word and followed by a definition of the component.

BARB = A hose barb of the size indicated in the text, preferably with a threaded flange and nut for mounting ease, usually to the LID.
BOTTOM = The supporting base with barb that is supplied by AP with their complete TWP unit.
CDISK = The black filter disk supplied in some AP TWP units below the carbon bed.
FLOSS = Any Dacron or polyester filter floss material.
FOAM = Foam disk, a component of the AP TWP unit, usually used in pairs as a sediment filter.
LID = The top or bottom cap of a replacement cartridge as furnished by AP.
PAD = The compressed floss filter disk separating the carbon from the mixed bed in most AP TWP units.
PCR = Plastic Canvas Rounds, a fairly rigid plastic mesh disk purchased from most sewing and craft stores for needlepoint work and cut down to fit snugly inside the TWP cartridge housing.
TOP = The cap with barb that is supplied by AP with their complete TWP unit.

NOTE:  In most cases, you may substitute the TOP and BOTTOM components for a LID and BARB assembly with an appropriate sized barb.  All in-line reactors are fed from the bottom and exit from the top.  All in-sump reactors are fed from the top and have a PCR or two, as the bottom component.

Molecular Absorption Reactor:  The first and most important reactor assembly for tap-water purification purposes will take the place of  PBM's Fin'l-Filter.  The excellent filtration component of the Fin'l Filter is their molecular absorption disks, of which, the company, Poly-Bio-Marine, Inc. has made readily available to all aquarists in a convenient 12 pack.  The diameter of the AP TWP cartridge, coincidentally, just happens to be the ideal size for properly holding the Poly-Disk stack or pile.

Construction begins with an empty TWP cylinder and follows in this order, install TOP, insert PCR from bottom and push toward top seating firmly, install any one of the following; CDISK, FLOSS or FOAM, filter components and seat firmly.  Install 12 Poly-Disks keeping them as loose as possible with surfaces touching, do not tightly pack them down against each other.  If you have a PAD available, it should be placed in the cylinder next, else 2 FOAM filter disks.  The remaining area is filled preferably with rinsed zeolite if you have it available, if not, this area can be filled with aquarium grade well rinsed charcoal.  Finally, place a CDISK or 2 FOAM filter disks, followed by a PCR and then the BOTTOM.

This completes construction of the pre-filter, it can be put to immediate use directly ahead of the AP TWP DI column or columns, or immediately following the carbon cylinder if so utilized.  Under normal usage, the column should perform satisfactorily for at least a year.  It is not necessary to replace the entire set of discs when overhauling the unit.  Poly-Disks change color progressing from yellow to brown to black as they remove contaminants from the water supply.  They can be washed and reused several times or heavily cleaned by soaking in Hydrogen Peroxide, rinsed and returned to the column.

When servicing your molecular absorption reactor, keep all the disks in their original placement order.  When the bottom disk or disks turn black, discard them and add the new disks to the top of the stack.  Spent disks may be washed and used solely as mechanical filters in or on other devices around the aquaria, spent Poly-Filter Pads are better suited for this purpose than disks.

In-Line Chemical Reactor:  Chemical reactors may be utilized to hold any type of media you desire from denitrification to phosphate reduction or carbonaceous material.  Construction is simple and includes the TOP followed by 2 FOAM filters and if available a CDISK.  A layer of FLOSS usually precedes and follows whatever media you choose to fill the unit.  The final FLOSS layer is followed by another CDISK and 2 FOAM filters then the BOTTOM.  PCR's usually come several to a pack, so it is advisable to consume these by utilizing them as the first and last piece of filter material in all reactors.

In-Sump Chemical Reactor:  Efficient use of AP TWP cartridge housings can be best achieved by utilizing them as in-sump reactors.  They can be pressure or gravity fed with the latter use being most common.  Gravity fed units may utilize an overflow hole or tube located near the top to indicate when cleaning of the unit should be performed.  Only one LID and BARB assembly is used to build an in-sump reactor.  The outlet of the reactor should be located above the normal water line of your particular sump.  Their are numerous ways to mount or support one or more reactors in your sump, plastic coated coathangers make great over the edge hangers, a piece of plexi strategically mounted parallel to the sump frame and even plastic soda can holders from your car will suffice.

Construction of the in-sump reactor is similar to the in-line reactor shown above and consists of the LID and BARB assembly, followed by 2 FOAM filters and if available a CDISK.  A layer of FLOSS usually precedes and follows whatever media you choose to fill the unit.  The final FLOSS layer is followed by another CDISK.  Normally FOAM filters are not placed at the outlet, but the final filter and support that holds the media in the cylinder is one or two PCR's, one is usually sufficient for gravity fed units and two are recommended for pressure fed units.

In-Tank Protein Skimmer:  Use a PCR for the base of the protein skimmer.  A small clear plastic bottle 3/4 to 1 inch in diameter with the bottom cut off forms the foam column.  The neck end of the clear plastic bottle is screwed through a hole drilled in and affixed with silicone into a LID at the top of the protein skimmer.  A cut off cylinder section or plastic cup, drilled to fit over the clear plastic bottle is glued to the cap and forms the collection cup.  A hole is drilled and a drain tube is snugly fitted to the collection cup and run to waste.  A wooden airstone is placed in the bottom of the unit and the rigid airline run through the clear bottle and out the top where it is connected to flexible airline and attached to an air-pump.  For aquarium water circulation a 1/2 to 3/4 inch diameter hole is made in the side of the protein skimmer about 1/3 the height of the column measured downward from the LID.  Proper foam column height is adjusted by moving the in-tank protein skimmer up or down in the aquarium.  In-tank protein skimmers are not as effective as free standing units of the same size.

Free-Standing Protein Skimmer:  Due to the design possibilities and construction techniques that may be utilized, I will omit a detailed plan to construct a free-standing protein skimmer.  However, I will mention a few pointers.  To insure countercurrent operation, the outlet tube if installed in the top LID should run from this LID downward to within 1/2 inch of the bottom LID.  To prevent collection cup overflows, a separate sleeve, larger than the foam tube, extends about 1/2 inch below the top of the foam column tube in the center of the collection cup, it should be centered over this tube and glued to an easily removable cap.  The air vent or outlet should be outside of this overflow protection sleeve.  The air inlet barb should be a separate attachment to the LID.  Usually, only the input flowrate needs to be controlled.  If your pump does not move sufficient water to hold the water level in the unit 1 inch below the LID when the air-pump is off, you may need to move the control valve to the outlet hose.  Use an air control valve to maintain the foam level in the foam tube about 1 inch below the top exit of this tube.

Many other reactors can be constructed from the versatile cylinder provided with the AP TWP.  Their discussion is beyond the scope of this instruction manual and therefore omitted.

The Formula

I have read and understood the directions for recharging DeIonization columns and desire to mix my own Recharge Fluids utilizing the required chemicals at the risks involved in doing same.  I hold neither the Author of this document nor Reef And Invert Aquarium Resources, their Parent or Subsidiaries, liable for any damage or injuries related to the use of or mixing these chemicals myself.

To obtain the FORMULA click on the following agreement.

I have read and agree to the above paragraph, in order to obtain this FORMULA.

Valid HTML5

Valid CSS level 3