Green algae stain spa stone wall

[dphanes]

We have a stone spa attached to our pool and some of the stones is turning green. Trying to figure out how to get the green off. Am sure anything that is sprayed on the stones will drip into the pool water.
Help…

 

[mknauss]

Spray chlorine on it and brush it.

I assume this is your spa spillover. Stacked stone looks pretty, but is a maintenance issue when used for spillovers.

 

[IceShadow]

Dilute some bleach, put it in a bucket, get an old toothbrush, and go to town on it.