Help! Trying to treat my pool but situation is getting worse


New member
Jun 15, 2010
Hello all - I'm in big trouble. I have a inground liner pool. Last week, I noticed some small black algae attached to my wall at different spots. I super shocked it and scrubbed a few days in a row and thought things were going good, but not resolved. So, I spoke to my pool dealer and he suggested adding "black treat" (sodium bromide). I followed the instruction which said to add 2 gallons of hydrogen peroxide. I did. BTW, my water was crystal clear at this point, just small black algae on wall. I waited 8 hours and checked chlorine level, it was low so I added a bag of shock and boy was I shocked. The entire pool water turned bright green. I am so upset and don't know what to do. Any help, please please please. This just happened two hours ago. I've been looking online and have not found a similar case. Obviously there was some sort of chemical reaction, but what? Do I need to empty pool?


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Start by digging the empty containers out of the trash and see if you can't find the ingredients. If there's copper, that's probably your green. Folks here can talk you through it, but only if we have certain information. And that's going to require accurate water test results. Do you have a test kit? First thing to look for is free chlorine and pH. Too high FC will affect readings, and pH will cause the metal to go green in the water.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
When the pool turns a clear transparent green after adding chlorine it is almost always caused by metals in the water, either copper or iron. A startup dose of sequestrant should clear up the green. It is possible that your spots are also being caused by metals, though that is less clear.


TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
SWSuburban Chicago, IL
I Joecus,

I hate to say it but the pool store is giving you bad advice. First off, Black Algae is virtually unheard of in a vinyl liner pool, and the sodium bromide was unneccessary.

Can you please post a full set of results, including metals? Have you recently used algaecide that may contain copper?

I realize since it's late you won't be able to have the water tested until tomorrow... but don't worry too much tonight this is fixable. :wink:

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