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Anion Exchange Resin:
Anion exchange resins must be regenerated separately from the cation resins, and this time using a 4 percent base solution (with a high pH). You must now prepare a 4 percent solution based on the method already described, using Sodium Hydroxide. This can usually be obtained from hardware stores as caustic soda, as it is also used to unclog clogged drain pipes of sinks.
Because this is a stronger chemical, please follow the directions on the can or bottle or container very carefully. You are not doing anything dangerous, but you must be careful, that's all. Keep the mixture and the chemicals away from children. Dispose of the effluent safely by diluting it even further.
Run the mixture slowly through the resin, again at about 30 gallons per hour, and this time use 3 gallons per pound of resin you have. Dispose of the effluent safely and immediately. Do not store it. You can not reuse it. Flush the unit slowly to remove all remaining caustic material, lest the pH of the water you will treat will be too high.
When should you regenerate ?
- when the resin is no longer removing all the elements you want to remove, e.g. nitrates and phosphates.- when total dissolved solids measure more than 30-40 ppm. Small, inexpensive, handheld units measuring TDS are advertised in hobby magazines, or can be bought from scientific supply houses.
Single de-ionizing Units:
Single column de-ionizers, using a mixed bed (2 resins), are regenerated in exactly the same manner as double units, but first the resins need to be separated.
First you must remove the resin from the container. Place it in a larger one, at the bottom of which you have placed one or two air stones. Place filter floss over the resin, as well as a rather tight fitting lid with some holes in it, for the water to come through.
Now pump water slowly into that vat, from the bottom, and blow air slowly as well at the same time. The action of the water and of the air will make the lighter anion resin migrate to the top, and the heavier cation exchanger will go to the bottom. In the middle a small band of mixed resin will remain. Old columnar protein skimmers make ideal containers to do this, as long as you pump the water in through the original "outflow" of the skimmer, and let the water come out where it would normally have gone in when the unit is run as a skimmer (you are in essence reversing the in and out).
Remove the anion resin and treat as indicated in the previous section. Remove the mixed resin layer and dispose of it. It cannot be separated easily, and can not be recharged. Since mixed bed exchangers contain equal amounts of both types of resin, the mixed layer is in the middle. Remove the cation exchange resin, and treat as explained in the previous section.
Never deionize water to which salt has been added already.The better the water you start with, the longer your resin will obviously last.
Some Hobbyist first use reverse osmosis, then deionize.
Regenerate frequently. The effluent water will always be better. In double units always run water through the Cation resin first.
Flowing water through activated carbon before D.I. extends the resin life.
Flowing water through carbon after D.I. "may" purify the water more and better. It is better to put it before the D.I. unit.
Flowing water thru Poly Filters after D.I. will purify the water even more.
Flowing water thru Poly Filters before D.I. will extend the resin life.
Remove all water from D.I. units that are not in use, and/or stored.
Turn units not in use upside down in a bucket or so.
If water remains in a unit when not in use, it will stagnate and smell because of anaerobics.
Before each session of D.I. flush the unit with some water.
If the outcoming water smells at first, flush it until it doesn't anymore. Or regenerate the resins.
Check the D.O. of the outflowing water periodically. If need be, aerate the water to re-increase the dissolved oxygen.
Be very careful with the regenerating compounds.
Keep them away from children.
After regenerating, dispose of effluent safely and immediately. See the main text for methods of how to do so.
Always rinse resin well after regenerating to remove acids and bases, lest the pH will be too low or too high for the water to be used.
Of all the chemical filtration methods available to the Small Reef Hobbyist, perhaps the easiest to use, and certainly the easiest to install and include in the filtration set-up, is the very well known Poly Filter from Poly-Bio Marine.
A pad, or disks, are placed anywhere in the water flow, as long as they are in an area where water flows "through" them. They will work too if water just flows "by or over" them, but they will give you their full efficiency if water flows "through" them.
Poly Filters are a synthetic material impregnated with hydrophylic polymers designed to remove pollutants from the water by absorbing their molecules.
Some of the compounds these pads or discs will remove, or reduce, or keep in check, include the following :
The pads, or discs, can be placed anywhere in the water flow. Moreover, not all of them have to be in the same spot. You can distribute them in several locations, wherever you have space, and wherever the water will flow through them. Additionally, feel free to cut them up in smaller pieces of any shape, and make them fit the space where you have decided to place them.
They change color as they become progressively loaded with the compounds they have removed, they start to change color. This allows you to determine when, in fact, it is time to replace them. Because they may also trap dirt, their true color may be masked. It is, therefore, a good idea to clean them once a week to remove particulate matter that they may have trapped. Rinse them under warm tap water and squeeze to remove dirt. Evaluate the color after you have cleaned the pads or discs. If they start to turn medium to dark brownish, it is time to replace them.
Here are some typical colors the pads or discs may take on, and the products that are involved. This list was provided by Ken Howery of Poly-Bio Marine Inc. :
I have personally used, and still use, Poly Filters for years. I would not run a tank without them. This is a truly superior product that you must include in your filtration set-up. I use a lot of them. Sometimes one pad per 25 gallons of water. If there was such a thing as a Reef Tank Best Product Award, Poly Filters should get it. Poly Filters are widely available and, because of their relatively long life, are a very cost efficient chemical filter. The pads, when new, are white. Do not buy pads that have a faded yellow color. They may be old, and although they will still work, they will exhaust themselves rather quickly. Make sure the package is closed when you get it.
Some locations where you could place a Poly Filter :
- in the sump, close by the pump intake opening,
- in the sump in a special compartment that is already there, or that you
have added,
- in the pre-filter box, or overflow syphon arrangement,
- in a canister filter,
- in a chemical module of e.g. Lifeguard or PEP filters,
- in the overflow corner box, if your tank was drilled for one,
- inside the tank in an inconspicuous area with good water flow, for
example behind rocks, or dead coral,
- and of course in the special canisters sold by Poly-Bio Marine.Some Hobbyists dedicate a Poly Filter to remove copper from hospital or treatment tanks, and use that pad only for that purpose. Such is, of course, an excellent idea. So is having such a small tank running at all times. Just in case !
If you use Poly Filters to remove medications, use one pad per type of medication and remove it after the treatment is completed. Store the pad after letting it dry, and label it so you know what medication you used it for. Poly Filters do not remove gasses, so they will not affect your dissolved oxygen and carbon dioxide levels. That is a boon, because freshly added carbon will, for some time, lower the D.O. levels. The latter, in turn, affects your redox potential.
Keep a few spare pads around. When something just does not seem right with the tank (and such happens, believe me), add one or more Poly Filters immediately. Of course you must, in such cases, also check your water quality parameters, and make adjustments if necessary. Sometimes, however, things seem not right, and no cause can clearly be identified. As a precaution and partial or complete remedial, Poly Filters should be added to the system.
I indicated already that Poly Filters should be cleaned. Because even in the best filtered tanks small particulate matter always abounds, it is necessary to do so regularly. Make it part of your regular maintenance routine. Your water quality will benefit from it. And, when keeping Reef Tanks, it all boils down to water quality.
When placing Poly Filters in a canister filter, position them between layers of filter floss. This will reduce the amount of particulate matter trapped on the pads or disks, and make them perform more efficiently for you.
As far as I have been able to determine, Poly Filters will not remove ozone, and Poly-Bio Marine are looking into this. However, a Poly filter that has been in use for a while will reduce it, mainly because of the particulate matter it has trapped. Some carbon is, therefore, still necessary if you run a skimmer, or a reactor, with ozone injection.
We referred to pads and discs in this section. Although they both perform the same function, the discs are a much stronger variety of the medium. The latter also explains why they are more expensive.
[Albert J. Thiel requests that you make a $5.00 donation to the New Mexico School for the Visually Handicapped Children, 1900 North White Sands, Alamagordo, New Mexico 88310 (or other charitable group) if you download the entire book. This would be in lieu of the standard purchase price for this publication.]
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