This is new...could it be black algae?

[davidyal]

For years I've struggled with some green algae. I used Algaetrine on occasion, but always struggled.

I replastered my pool (pebble tec) during the fall, so this year after opening I got everything balanced and used a PoolRX as my algaecide. For 3 weeks it was sparkling. I was so pleased. Admittedly, I let the chlorine get too low, and then suddenly all these small black splotches appeared. They didn't respond to any brushing, however if I got inside and scrubbed with a chlorine tab they seemed to go away. There are dozens left to scrub off.

I'm so puzzled how this could happen with a brand new PoolRx in the system. The water is still clear and sparkling- and I'm keeping chlorine around 2- but nervous about what's going on and have lots to clean. Any suggestions how to approach this?

David

 

[Newdude]

I'm so puzzled how this could happen with a brand new PoolRx in the system

. Admittedly, I let the chlorine get too low

I'm keeping chlorine around 2

Any suggestions how to approach this

Follow the FC/CYA Levels. Religiously. Never ever approach minimum. Never think about it. Or wonder about it. Or DREAM of ever getting close to it.

Being a PoolRx user, I kinda already know the answer, but how are you testing ? Your results are only as good as the test data. Strips and stores just can’t cut it.

 

[Katodude]

It does look like black algae. You are going to need a wire brush and get in there and scrub it all off.

I would then get a pump sprayer full of the highest concentration LC you can find and hit the spots after you scrubbed them. Then you will need to keep elevated FC levels for several weeks. And keep brushing those spots.

As @Newdude said, get a good test kit you will need it.

And throw out that PoolRx before it stains your beautiful pool.

 

[proavia]

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It's most probably some type of algae. A SLAM Process and diligent brushing will get rid of it.

The algaecide and PoolRX aren't helping you at all.