Another is high pH. At least that is what happens to me in the lilypond,
when I note the WH not doing well and the SA doing great, my pH is always
way up. I acidified it yesterday, and things are already looking better.
~ jan



It's too late for the WH. Shaking the roots of the water lettuce seems
to dislodge the algae. I really try to avoid adding chemicals to the
pond.

Algae boom most of the time are due to phosphorus. Do you remove old
plant from your pond? This will give more space for new plant to grow
and remove phosphorus from water.

Regards,
Wong


(Do you know where your water quality is?)