Two gallons of cutrine is probably about the right dosage considering the timeframe and depending on the depth of the pond. The label says 2.4 gallons for 4 acre feet. Double that dosage for chara.

In my experience, the effect from a treatment of cutrine plus only lasts 5 or 6 weeks.

Incoming nutrients from the orchard definitely sound suspect to me.



"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking