Hi Tabitha;

Be cautious about your pH. As your chlorine level goes above 10, your pH readings, if measured with phenol red drops, will be less and less accurate. At 18 ppm . . . unless you are using a calibrated pH meter, you really don't know what your pH is.

Regarding the algae -- are you saying that you have algae in the pits and rough places at the water line?

If so, lowering the water level, and using a 1:10 spray of polyquat will probably work. Just make sure you use a CLEAN sprayer, with no herbicide or pesticide residue.

Or, if you've got an old clean sprayer that you don't mind ruining, spraying with straight bleach, and then 'pressure washing' with a hose and nozzle and the re-spraying will probably work.

But, it depends on how deep the rough spots are: you can only kill algae you can reach!

Once the algae's gone we'll need to see what the situation is with your pH.

Ben
"PoolDoc"