slightly cloudy pool?

[archer636]

pool has been slightly cloudy for a few weeks- any idea why? last shock was over 2 months ago and cleared up after that, so it's not an after-shock issue.

CC=0
FC=6.5
CYA=60
OCLT<.5ppm
PH=7.4-7.6
TA=70

 

[jeffchap]

How did you obtain your test values, and how do you chlorinate your pool?

Most often, cloudiness is a symptom of a nascent algae bloom resulting from insufficient FC level relative to your CYA.

Your numbers look good, which is why I question where you obtained them. If they are the result of pool store testing, I would suspect them, as pool stores are wildly inaccurate, especially concerning CYA. Our method here relies upon accurate testing with a reputable test kit.

 

[archer636]

How did you obtain your test values, and how do you chlorinate your pool?

Most often, cloudiness is a symptom of a nascent algae bloom resulting from insufficient FC level relative to your CYA.

Your numbers look good, which is why I question where you obtained them. If they are the result of pool store testing, I would suspect them, as pool stores are wildly inaccurate, especially concerning CYA. Our method here relies upon accurate testing with a reputable test kit.

I use Taylor complete FAS-DPD kit. I find the CYA test highly subjective- I have tried using the 50ppm calibration liquid as reference but I am still not confident about the 60. Should I raise the FC to 9 for a few days see how it goes? I use 10.5% sodium hypochlorite.

 

[jeffchap]

If your CYA is as low as 50, you could raise your FC to as high as 20 and it would still be safe to swim in. I'd do that for a couple of days and run the filter 24x7 and see how it looks then.

If you think your CYA is really 60, go to 24 with the FC.

Let us know how it goes.

 

[archer636]

If your CYA is as low as 50, you could raise your FC to as high as 20 and it would still be safe to swim in. I'd do that for a couple of days and run the filter 24x7 and see how it looks then.

If you think your CYA is really 60, go to 24 with the FC.

Let us know how it goes.

maintaned FC=20 for a few days and I think it helped. Now how do I figure out what level to maintain over the long run? (since 20 will cost a lot of chlorine and test material!)

 

[jeffchap]

Your target should be 6 ppm, and never let it drop below 4. But before you let it drop to that level, you should perform an overnight chlorine loss test to insure that you've eradicated all of the algae. See http://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt for details.