Re: Cationic Polymer - Pool Clarifier from HTH -Questions
HTH used to list the ingredient as sodium polyacrylate but now just say cationic polymer. Don't know if they changed the forumula or not. Sodium polyacrylate is the same stuff that Clorox puts into their 'new and improved whitening formua' bleach that has gotten much discussion on the forum in the past. Sodium polyacrylate is a cationic polymer (there are many chemicals that are in this general group) which means it is a long chained molecule with a postive electrostatic charge (cations are postively charged and anions are negatively charged) and will bind with particles in the water that have a negative charge. This is how it works to clarify the water. The negative particles clump together on the polymer and are now big enough to be filtered out faster.
There is a downside to using polymeric clarifiers, however. If you overdose they will actually cause the water to cloud and no amount of filtering will remove the cloudiness. This is because an overdose causes the particles to go into a 'colloidial' state. This means they form very small, dispersed particles in the water that are too small to filter because the polymer is now acting like an emulsifying agent. For an example to explain what I mean let's look at mayonaise, which is basically just oil, water,, vinegar, and egg. If you just mix oil, water, and vinegar it will separate on standing into an oil layer and the water/vinegar layer, even if you mix for hours but when the egg yolk is added it emulsifies the oil and water/vinegar and the oil forms finely dispersed colloidial droplets that do no seperate out from the water/vinegar. They just stay in suspension and you have mayonaise! Much the same thing can happen if you overdose a polymeric clarifier (the particles/polymer become collidial) so if you decide to use one be sure to follow the dosing instructions.
I personally do not think that clarifiers are needed. Some of my customers do say they help with sand filters (but adding DE to your sand filter will probably work much better!)
If you have a cartridge filter the chitosan based clarifers (like SeaKlear) seem to be more effective than the synthetic polymers from the feedback I have received from customers (and from what I have read about them).
If you have a DE filter I personally don't think a clarifier will do much at all but probably won't hurt anything.
Hope this info is helpful.
Edit: Although some clarifiers state on the package that they help remove metals I really don't think they are that effective unless the metal is actually precipitated out of solution as a particulate suspension and not just an ion in the water. (Richard, your thoughts on this would be appreciated) If you have a metal problem then a seqesterant is what you need. If you are concerned about using a phosphonic acid based sequesterant (HEDP) there are some on the market that are based on the chelator EDTA such as NaturalChemisty's Metal Free. I personally don't think the HEDP based sequsterants cause problems unless you are one of the very rare individuals that have a problem of recurring algae from high phospates that can't be controlled in any way except with a phosphate remover.
Last edited by waterbear; 09-29-2006 at 11:31 AM.
Reason: additonal info
Retired pool store and commercial pool maintenance guy.
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