The half-pond, 7-14 day waiting period is a conservative rule-of-thumb by the chemical manufacturer. The theory is to avoid a big oxygen crash if all the algae dies and decomposes at once. I have also seen instructions to do 1/3 of the pond at a time, so the guidelines are pretty loose.

I assume you are talking about filamentous algae on the surface? Do you have aeration? What is the alkalinity? If you follow the dosage rates and spot spray on the actively growing green algae only, then you could probably do the entire pond at once. Trout are the most susceptible to oxygen depletion. Carp, minnows, and frogs will probably be fine.

I spot spray my entire 0.62 acre pond at once when the algae is minor. I have aeration and had trout in the past.

If you hired a professional, would he do it all at once or come back in 2 weeks? I suspect he would do the entire pond in one visit. Just a hunch...

I did 1/2 pond increments when there was heavy FA infestation like this:

[Linked Image from i.imgur.com]