Do I have black algae?

[emromig]

I have a concrete pool with a fiberglass lining on the sides. Over the past many months my pool has developed tiny black spots on the entire surface of the floor. The frustrating thing is I have a weekly pool service and I have asked them repeatedly about the spots, but with no response. I finally bought a pool maintenance book and realized that I might have black algae.

How do I know if I have black algae?

Please help with any suggestions. Thanks!

[mr_clean]

Theres two things you can do to find out if this is Black algae or metal/mineral problem.

take chlorine tab and rub small area and then place tab on top and let sit for 3-4hrs. If spots start to get removed it's black algae.
You can get a granular or liquid treatment to get rid of black algae. When you have white plaster granular works well. Good chemical balance in future will help keep it away.

Put 1/2 pound of pH reducer granules in a white sock. Shut off the filter. tape the sock to end of pole with duck-tape and drop the sock onto a stained area and leave in place for 15 minutes. Use the pole to move it around after 15 minutes. If improvement is seen, the problem is minerals.
Lower the pH to 6.5 7.0, by the addition of muriatic acid. Add a bottle of Metal remover, Let chlorine level drop and when doing this you can use PolyQuat 60 algaecide to keep algae away. Once the pH is lowered, use the brush to scrub the stains. Keep the filter operating and if possible, by pass. Periodically check the pH to see if more acid is required. Once the stains are removed, add another dose of metal treatment, prior to raising the pH.
You can also start using metal treatment as prevenative in future

[Guest]

I tried the trichlor tab, but it left a yellow/brown stain on the steps and the black spots are still there. How do you remove stains from a chlorine tab? I will try the metal treatment you mentioned on the black spots.

Thanks!

[mr_clean]

This would be caused by a High mineral/metals level in water. You can add a metal remover to pool water.

[Guest]

Black Algae if from lack of brushing everyone should brush the pool once a week! Algae is like dust just because you cant see it right away doesnt mean that it isnt there! If it was black algae you should have brushed it REALLY good before you put a sock treatment on it to kill it...Since it turned a brown color that leads me to believe that you have killed it ...Algae usually turns a brown color when dead..If it was a metal stain like from manganese in the water it usually turns the whole pool black.....

[mr_clean]

pool user did you even read post's or are you drunk?

[South TX Poolguy]

Turning a whole pool black would be interesting. Drunk or not. Let me know if you can cheaply turn white plaster to a baby blue cheaply.

I have a friend who claims that putting borates into a pool is getting rid of the black algae. He is not shocking or brushing.