High CYA and Persistent Algae

[bthoward]

First off, thanks for the continued advice. Just checking to see if I am following your instructions correctly.

I held the FC=25 and PH=7.4 for a week and there were little to no signs of any algae. The past couple of days I've let it drop to 21 and now there were signs of algae growing on the walls. Should I just brush and raise it back up past 25 again for a bit longer?

[aylad]

If you still have algae in the pool, then you need to raise it back up and hold it there, past the point where you think all the algae is gone. One good test for when to let it drop back down is when you can test at night after the sun is off the pool, and test again in the morning before the sun is on the pool, and see if you've lost chlorine overnight. If so, then you still have something in the water consuming it, so don't let it drift down yet.

Are you also putting any brushes, poles, pool toys, etc. in the pool while it's being shocked, to keep from re-introducing algae when you use them?

Might want to consider the use of Borates at 50 ppm, which acts as an algaecide and can be used in conjunction with regular shocking, HOWEVER, since Pooldoc has ponted out that you need to keep your pH low for now, I'll let him advise you on whether that might help in your situation.

Janet