Closing Pool - Polyquat Question


LifeTime Supporter
May 5, 2010
I have a 17,500 gallon inground fiberglass pool. I just purchased a 32 oz. bottle of 60% Poly {oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride}. How much should I use as I prepare to close the pool? The whole bottle?

17,500 gallon
Sand Filter
South Arkansas

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
Use at least the amount specified on the bottle for "initial dose" which I believe is 9 ounces per 10,000 gallons. Do not use more than the "visible algae" dose which I believe is 16 ounces per 10,000 gallons. If you use the procedure where you shock with chlorine first, let the FC level drop, then add the PolyQuat, then if the water is cold it will last quite a while since the chlorine will eventually drop to zero (if you don't maintain it, assuming you get hard freezes and fully close your pool over the winter) and the PolyQuat will stick around for a long time especially if the circulation gets shut off (PolyQuat is a clarifier so will tend to get caught in the filter if there is debris to be cleared).


TFP Expert
In The Industry
Jun 12, 2009
Exeter, PA
I would only use the polyquat if you have a mesh cover though. If you have a regular tarp cover or solid cover that is in good condition in most cases it will open just as clean and clear as you closed it. I only use the polyquat on mesh covers as an attempt to have less algae on the opening.

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