Black / Brown algae

[David Kol]

Here are 2 pictures of the problem. These patches are more towards the outer edge of the pool. 24 ft pool, and the problem is fairly well confined to the outer 6 or 7 feet. Approx 6 to 7 feet from the center out has no noticeable problem (yet) As the cl level is increased, the darkness of the patches starts to go away.
I am now working on getting the cl to the range of 15ppm (as suggested here). Should I work on lowering the PH from the 7.9 now, or what until I get the CL level up.

Thanks

David

[gregugadawg]

black algae isn't going to grow in a vinyl lined pool, it needs a rough surface to attach on to as in a plaster surface. Also black algae is going to be no larger than a quarter in diameter. It is possible to be brown/mustard however that easily brushes up but is persistent. Try to rub a vitamin c tablet on the discoloration and see if it comes up, if so then it is a stain.

[David Kol]

Rubbing, scrubing, brushing had no effect on patches last year. This year we have rubbed with the brush on the vacuum head, and you see ZERO improvement.

The readings this morning after adding bleach yesterday based on the calculator, and acid for the ph late last night, are

cl 14PPM
ph 7.4 -7.5
cya 30-35 (subjective to when the black ball is not visable)

david

[CarlD]

David,
Now, I believe, you have to keep up and maintain the regiment of high CL, daily brushing and vacuuming--that almost looks like a mold there, but high chlorine levels should kill it. I doubt ascorbic acid will do any good to those patches.

I believe it will just take time, persistance, and lots of bleach.

[gregugadawg]

have you tried to rub a vitamin c tablet on those STAINS yet. that is not algae especially after i saw the pics. Black algae won't grow in a vinyl pool

[David Kol]

We will try the vitamin c tablet today. We need to pick some up.




cl level this morning 14ppm

David

[David Kol]

We tried the vitamin c rub, and saw no improvement. We rubbed the same spot 3 times.


Is it possible that this is a stain that starts to disapear or get masked at the cl level rises????

If i go to the bottom of the pool and scrub with a fairly stiff brush, I see no particles that are coming loose.

Water tempyesterday got to 84*. Added 1.5 gallon of 5.25% bleach last night to maintain approx. 15ppm cl. ph is 7.4 / 7.5 and cya is 30.

we are running the filter 24/7, and vacuuming daily.

below is a picture of the problem

Thanks

David