How can you get algae in a pool with perfect chemical balance?

[Seadweller]

Very interested in what might cause this.

 

[Texas Splash]

I can think of 3 reasons:
- Poor water circulation
- Lack of brushing all surfaces
- Inaccurate test results - specifically CYA or FC

 

[Wobblerlorri]

Not to mention all the stuff falling out of the sky, introducing airborne algae spores into the pool:
Rain
Bird poop
Dust
Leaves
Sticks with lichen on them

And then there's people and pool toys, with their own inherent nastiness...

 

[Seadweller]

So even with an FC of 6+, tested daily, the above could cause algae growth? One thing I do not to as regularly as I should, is brush the pool. That could be the culprit.

 

[kellyfair]

Hi, fellow Tampa neighbor! What are your latest test results?

 

[borjis]

If your cya is 50, a free chlorine of 6 is within the range.
4-8 FC.
What is your cya level?
What test kit are you using?

 

[Newdude]

I got a couple.

Stagnant water in ladders or water features.

Infested light niche that’s never been cleaned.

Bad reagents before expiration dates from not being stored in cool dry place giving wrong results

algae hiding under the protective biofilm it grew when it wasn’t brushed frequently enough.