In addition to pool school:black algae teachings, I've found this works to address small patches on flat horizontal to near horizontal surfaces.
Put ~1/4 trichlor puck in middle of mat with rib side of mat down. Cover area of combat with the mat.
Restaurant supply stores have these cheap. Else 18" x 11" ~$11 at amazon. They're the mats bartenders mix drinks over with ribs to keep glass bottoms drier.
Idea is that the mat traps high chlorine concentration over the algae patch. Chlorine can easily diffuse under the mat due to the ribs.
About 8 hours seems to work in an area. Ideally, wire brush before, during and after, but worked with only before and after brushing.
My pool wide FC is about 20% of CYA. E.g. 12ppm with 60ppm CYA.
Requires some finesse to position mat . Two extended grip tools (for reaching high shelves) are useful for holding puck and mat.
Pool sweep may displace the mat, as might swimmers
Might work on vertical surfaces. Hang mat with Alligator clips to ropes up pool side. Need some way to hold trichlor puck under the top edge of the mat.
YMMV.
Good luck!
Put ~1/4 trichlor puck in middle of mat with rib side of mat down. Cover area of combat with the mat.
Restaurant supply stores have these cheap. Else 18" x 11" ~$11 at amazon. They're the mats bartenders mix drinks over with ribs to keep glass bottoms drier.
Idea is that the mat traps high chlorine concentration over the algae patch. Chlorine can easily diffuse under the mat due to the ribs.
About 8 hours seems to work in an area. Ideally, wire brush before, during and after, but worked with only before and after brushing.
My pool wide FC is about 20% of CYA. E.g. 12ppm with 60ppm CYA.
Requires some finesse to position mat . Two extended grip tools (for reaching high shelves) are useful for holding puck and mat.
Pool sweep may displace the mat, as might swimmers
Might work on vertical surfaces. Hang mat with Alligator clips to ropes up pool side. Need some way to hold trichlor puck under the top edge of the mat.
YMMV.
Good luck!
