mold in my deck

[itybitybob]

I have black mold growing in the cracks of the deck around my pool. This is the first time I have found this in the ten years we have owned our home. It seems to be worse in the area that is not in direct sun light all day. I believe that my chemical levels are correct. I use chlorine tablets in a float thingee and have the only change I have made is in the brand of pool clarifier that I use. I have had a problem in the past with calcium build up in these areas in the past and now it's mold. What would be the proper way to remove the mold and prevent it for returning. FYI I am in Arizona so don't believe it's a humidity problem.
That's for any advise

[Bosch232]

Just to be clear, are we talking about the walking deck surface around your pool, or part of the pool (in the water)?

[itybitybob]

Sorry I should have been more clear. It's just above the water line in the pool. There are some cracks and rough spots that go from the water line to the deck. only about three inches. After some online searching I have learned that it is apparently called black algae. I guess I panicked a bit but what's disturbing is now I am not sure if my testing chemicals are giving me correct readings. I will now go have my water tested but it appears that I didn't have enough chlorine in the pool. Thanks for your response.