Dead algae at the bottom of the pool is not a sanitation issue -- if you keep your chlorine up, that's all that's needed.

There's an aesthetic problem, of course: it doesn't look good.

Perhaps more importantly, if you have small children they can disappear dangerously into really cloudy water.

But, from a sanitation point of view, if the green is gone, and the goo settles overnight, and the chlorine is kept up (3ppm or more), you're fine.

Ben
"PoolDoc"