Black Algae Help

[Txpoolgal17]

New-ish pool owner here and having trouble getting rid of black algae. (Or so I think it’s black algae).

I’ve followed the steps of getting my pH down, super chlorinating, and then scrubbing the spots with a wire brush, but they keep coming back or don’t disappear entirely. I use a Taylor water chemistry kit and my water levels are as follows - pH 7.8 (usually on the higher side but I add MA a lot), TA - 110, CH - 450, CYA - 30, temp - 83 degrees. I normally keep chlorine between 2-3 ppm using bleach, but I get up to 10-15 and leave it when I am trying to kill the algae. The algae has been in the pool for months now.

The pool and plaster is 16 years old, and I’m lost on what to do next.

Also, Is it actually safe to swim with small amounts? (Spoiler - we have all summer and are still alive). Thanks y’all!

 

[mknauss]

Welcome to the forum!
Have your read Black Algae - Trouble Free Pool
Also, a CYA of 30 in Midland I would think would be difficult to keep your FC from dropping below minimum. You say you keep the FC at 2-3 ppm, but your consumption each day would be 3-4 ppm, so be sure to follow the FC/CYA Levels
It is safe to swim in the pool as long as your FC is above minimum for the CYA.
Black Algae is cyanobacteria. So not actually algae.
I suggest you read ABC's of Pool Water Chemistry.

 

[Txpoolgal17]

Thanks for the reply! I will definitely read your links. I add bleach every evening and test every couple days, so I think my FC is staying in the range. We had battled high CYA (120+) when we first bought the house and got the pool, so I have been very careful about not getting to the same point as before. I didn’t consider that maybe 30 is too low.

 

[mknauss]

so I think my FC is staying in the range.

The FC of 2-3 ppm you state is the minimum. Your FC should never be going below 3 ppm.

 

[Txpoolgal17]

The FC of 2-3 ppm you state is the minimum. Your FC should never be going below 3 ppm.

I see what you’re saying. Keep between 4-6 due to the CYA being 30. Got it!

 

[Katodude]

So here is my trick. Get a mask and snorkel and a bamboo bbq skewer. I pick at the spots. Or use a small wire brush to do the same. Then I put LC in a pump sprayer and hit the spots that you picked at or brush with a high dose.

Repeat the next day.

Then keep your FC elevated as Marty suggests and you should be fine.

 

[ccbill]

You use the sprayer underwater?

 

[Katodude]

Yep!!