Polyquat properties - how much is enough?

[amjohn]

I live it Northern TX in a rural area and this is our first year, first pool. I am going to start out this winter not covering the pool and running the pump when it freezes (after reading every possible post in this forum on winterizing). If we actually get winter, then I may drain the pump and filter, but still do not plan to cover the pool at this point. I figure if I change my mind, I can always order a cover. I have learned so far with BBB that less is more.
Our winter weather can be just about anything. We can have ice storms, blasting winds, temps in the 20s. Or we can have 90 degrees, hot, sunny with high winds. Or we can have both in the same week- the one constant is change.
My question concerns the polyquat:
If I am going to run the pump a little each day this winter and at night for freezes, do I need to add polyquat?
If I do winterize the pump, I plan to add the polyquat first, since there will not be any circulation in the pool. But what makes polyquat go away, as I assume it does eventually? Does it break down in the sun like chlorine? When we get warm sunny weather, will the polyquat break down, and if it does, how do I know when to add more and how much to add?

 

[chem geek]

You should have either chlorine or PolyQuat in the pool to prevent algae. If you go with PolyQuat, then chlorine would break it down over around a week or so which is why you normally add more weekly. If you don't have chlorine in the pool, then the PolyQuat should last longer. It should not break down in sunlight. It will mostly go away by clarifying your water and getting caught in the filter. How long this takes depends on how much "junk" their is in the water to attach to the PolyQuat and then get caught in the filter. My rough guess is that without chlorine, the PolyQuat might last a month. It certainly won't last an entire winter.

Buckman Labs (who make PolyQuat) recommends first shocking the pool with chlorine to get rid of as many organics as possible, let the chlorine level drop, and then add a large dose (like an initial dose or more) of PolyQuat. When adding PolyQuat, you need to run the pump for 24 hours to ensure it gets thoroughly mixed as it is quite thick (viscous). After that, you can do your normal circulation.

 

[amjohn]

Thank you for the answer chem geek. I figured it had to break down somehow.
Would you recommend using polyquat if we are going to keep the pool "open" for the winter then, or would it be better to maintain it on chlorine? The water will get cold, but not Minnesota cold- more like 50-60 degrees, with occasional 10 degree excursions depending on weather. I am told that is enough to retard algae growth. Not sure what the chlorine levels will do- I add chlorine every other day now, with water temps in the 80s - air temps have been pretty mild for our area.
If I do end up winterizing the pump, polyquat certainly seems the way to go. However:
If polyquat will only last a month, and if the pump is removed for winter, how do I mix the additional monthly doses of polyquat? If I dilute it to add it in a 5 gallon bucket, then brush the pool once it is added, is that sufficient?

 

[chem geek]

Cold water alone will not stop algae growth, though it does slow it down. If you think you can add chlorine every now and then over the winter, then that's all you need to do and you won't need any PolyQuat. That's what I do over the winter when the water temp gets no lower than 45 and is usually around 50-55. The chlorine usage is very, very low due to the colder temperatures. I only have to add more about once a month or perhaps every 3 weeks during the winter, but I have an opaque cover so don't have any loss from sunlight. Even so, with the cloudier days and lower sun angle in the winter, I'd expect your chlorine usage to drop by quite a bit.

If you don't have a pump, it's really hard to use PolyQuat since it doesn't mix readily as it is so viscous. I'm not sure if your pre-dilution of PolyQuat in a bucket would be sufficient. If you were going to add something on a regular basis, chlorine (chlorinating liquid or bleach) would be far easier as you could just use a pool brush to mix up the water after adding it around (in this case, you wouldn't add it in one place but would spread it around and then brush to mix up the water multiple places around the pool). I suppose which way to go (PolyQuat or chlorine) depends on how quickly your chlorine drops and how frequently you are willing to add it.

Richard