Black Powdery stuff in pool


Active member
May 12, 2010

I changed my pool over to the BBB method from the Perma Salt System back in the middle of May. And couldn't be happier!!! Pretty clear, sparkling water.
Here's my question: The last week or so we've noticed a black powdery (silt like) stuff in the pool, mainly in the liner creases. If you disturb the water over it, it disperses, it is not slimly. Walls and pool bottom feel great. Any suggestion on what it could be? My husband thinks it may just be stuff our sand filter is not catching. Until just recently it has been very dry, so when he moves it kicks up a lot of dust. I did have some left over Clariate from our Perma Salt days, it is suppose to make particles bonds and filter them out. He thinks it has helped it some.

Here is my numbers, I try to keep my FC between 4 and 6. I've not done a overnight FC test since May 27th. Will attempt one tomorrow morning, but I hear thunder.
FC 4.5
CC 0
TC 4.5
PH 7.8 should I lower this?
TA 100
CYA 50

Thank you,


Active member
May 12, 2010

Our grill is not close to our pool, and neither are our neighbors. But I will run this question by my husband.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
You can lower the PH now, or wait till it goes up just a little more and then lower it.

I expect that the black dust is either pollen or blown in dust of some kind. Since it is already settling to the bottom on it's own there is no need to treat it, just vacuum it up every couple of days.


LifeTime Supporter
May 1, 2010
Syracuse, NY
I had a similar thing recently. Mine was a bluish/black dust on the pool surface, sometimes it was massed together. I thought it might be some sort of insect eggs. I looked very close and they were extremly small bugs. They are gone now. I think the chlorine gave them a headache.

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