Black Spots...won't go away

[shorembo]

I am getting black spots that won't go away in the bottom and sides of my pool. When this happened a few years ago, I would use the chlorine crystals on the bottom and the spots would go away. This time though, things seem to have gotten worse.

As far as the spots go, they seem to collect in small pits at the bottom of the pool. I can take my finger and scrub the spot and I get a very dark green substance. There doesn't seem to be a hard cap on the spot.

When this first happened a few months ago I hit it with the chlorine crystals but it didn't go away fully. Subsequently, my salt chlorine generator went out and I have had to convert to regular chlorine. The spots increased so I went to the pool store over the weekend. I ended up dumping 5 gallons of chlorine, a bottle of metal control, and a bottle of super black algecide (copper?). I also scrubbed and vaccuumed. That took care of some of the stuff but it still is noticable.

At this point, I could try the chlorine crystals again, but I don't think that will do the trick. Any ideas? Is this really black algae? BTW, my pool surface is 6 years old (crystalcrete). Also, my pool is uncaged and gets leaves, flowers, and pollen for 3 seasons a year.

[shorembo]

For a little more information.....I dug out one of the black spots with my finger. It was not slimy at all....more like a green spinach.

[Guest]

Yeah, that spongy black algae is a real pain

Shock, brush, shock, brush and eventually it mostly goes away.

But it is always hanging around in some little hidey holes waiting for the day the chlorine drops to zero and BAM, it's back again.

[blobguy]

went to a pool store about the same problem and the guy said it could be the rubber in the solar heater degenerating.... only fix is to replace solar.
apparently the spots will feel different to algae if they are caused by this, not slimy.