Black Algae in grout.

[casabonita]

black algae in grout had this problem last year, had pool cleaned and regrouted, it has returned... whats best way to cure ??

[muss08]

brush it with a steel brush then- with gloves on- use bleach and a sponge to scrub it. wait about 10 minutes then rinse any exposed tile. it may be necessary to do this a couple times a day for a couple days. it sounds like your chlorine is being kept at a proper level which is why it came back. your free chlorine level should be at least 10% of your cyanuric acid (CYA) level.