black stain

[toni]

can anyone tell how to know if a stain is black algae or electrolysis

stain is on the floor of the pool around the return assembly attached with 16 stainless steel screws

it does not appear to be a plant it is definately a stain

[Guest]

can anyone tell how to know if a stain is black algae or electrolysis ...


put some ph decreaser (powdered) in a tube sock, tie it to a brush pole and place it directly on the stain for a few minutes, then swish it around on the stain...If the stain dissappears,it's mineral. If not, it's algae.