Rookie With Algae Problem

[poolgladiator]

Noticed an algae problem scattered along bottom of pool and under ladder.
It is a different color than the algae I have had in past years. More of a lime green. Is this mustard?

How do I correct? Do I need algaecide or will bleach correct?
Should I brush?

PS.....I use the 3 B's

18.000 IG vinyl Sand filter

Here are numbers before and after I shocked.....

Before Shock...........................After Shock
FC 15...................................23
CC 1.....................................0
TC 16....................................23
pH 7.5....................................7.5-7.6
CYA 90...................................90
Alkalinity.................................100
Temp 84.................................82

[CarlD]

I'd keep your number where they are (after #s) and brush the pool every day, vacuum to waste, and run your filter 24/7 till it's clear.

[duraleigh]

Yeah, with that high CYA, I suspect your Cl levels have, in the past, dipped low enough to allow that algae. I think you're in the process of eliminating it with just chlorine.

Algaecides get mixed reviews on the forum. I've never used them, others seem to have very good results. Your conditions might be ideal for the use of an algaecide as a preventative.....might not be a bad idea.

[poolgladiator]

Thanks Guys!
I'll keep the level up for a few days and heed your advice. I'm hesitant to add the algaecide.

[chem geek]

Were you really keeping your Total Free Chlorine (FC) at 15 ppm the whole time before this algae appeared? Even with 90 ppm CYA, the amount of disinfecting chlorine (HOCl at pH 7.5) would be 0.090 ppm which should be plenty to prevent algae (at least that's what we think, so getting more info from people like yourself is helpful).

The shock level of 23 ppm results in an HOCl level of 0.177 so let us know if this takes care of the algae.

Is the area where the algae occurred a place where there might be poor circulation?

Finally, do you have any idea what your borate level is, given that you use the 3B's which includes using Borax to raise the pH? If you don't know the level, how often and how much Borax do you add?

Richard