Advice Needed - High CYA, High Nitrates, and Lots of Algae

[aylad]

I typed a very long response to this thread about 1/2 hour ago, but when I tried to post, I got a message saying that the forum wasn't accepting new posts. So...I emailed it to Ben, but it's not here yet. Later this evening, when I can get back to the computer I was on at the time, I'll try again.

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OK, here it is...

What testing method did you use to come up with your test results? We very highly recommend drop-based testing here, because it is much more accurate than strips or computers are. Do yourself a favor and take a look at the K-2006 test kit in the link in my sig--it's going to be required if you're going to manage this pool with your CYA level that high.

You can fix the pool water in two ways...first, you can drain/refill part of your water to lower that CYA, or you can simply run a high CYA/high chlorine pool (which would be my pick of the two). Take a look at the "best guess chlorine chart" in my sig for a better explanation, but basically because your CYA is so high (due to the dichlor/trichlor use), you have to maintain higher chlorine levels to compensate. In your case, with a CYA of 160-ish (are you sure that's right?) you need to shock the pool up to a chlorine level of 25 ppm and hold it there, brushing daily and cleaning the cartridge as your pressure indicates, until the pool clears. It will become blue/cloudy at first, and then you can finish filtering out the dead algae After all the algae is gone, then you just have to maintain your chlorine levels between 8-15 ppm and you shouldn't have any further problems. (At this point, I'd switch to bleach, liquid chlorine, or a SWCG, though--if you keep using the dichlor or trichlor, that CYA is just going to skyrocket to the point where draining/refilling isn't an option).

I run a higher CYA pool than most folks around here--80-90 ppm, sometimes higher--and I like it that way. I don't have to dose everyday, and there are zero complaints from the swimmers I have about the water quality,.