Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants A balanced way to try algae/weed control

Plants can utilize sunlight at a low level, which is typically about 2x the reading on the secchi disk. I wouldn't use phytoplankton to achieve readings below 12" because at night they use rather than produce O2, and could be the cause of a fishkill during periods of low sunlight.

I'd prefer using dye to keep the secchi disk reading below 12", but I think the GC/Tilapia route is a better one to take and leave the opaciticy over 12".