The grout in patches at the bottom of our pool ,has turned black ,have tried scrubbing also put clourine granuals on top. no success. any other tips out there thanks.
You can get a product from HTH at www.spashop-france.com that is specifically for black algae in tiled pools. It is necesarry to kill the algae to its roots which it beds into grout. You may still have some staining afterwards but the algae will be dead and then you might like to regrout at some point. Beware emptying pools though.
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