IMO I would lightly treat the downwind surface scums or films with either properly diluted liquid Curtrine-Plus (or similar active copper based ingredient) or with liquid (10 part water:1part GCPro) of "completely" dissolved Green Clean Pro granular @ 1 cup/gal and thoroughly spray just the filmy area. GC Pro is hydrogen peroxide based as active ingredient and generally much 'safer' with no residual bound copper (metal) for the overall pond ecosystem.
Certain algae will move up and down in the water column based on type of species, wind amount, time of day, and or light brightness, intensity. It is advisable for obvious reasons to treat the surface 'film' when it appears early in development and when most dense (usually calm or light breeze) so one gets maximum numbers "trimmed" from the ecosystem. It is extremely difficult, impossible and not necessary to 'get' every individual. IMO pond conditions should be changed or modified to minimize future blooms of same species. Of course if you don't know which specie that is the problem you will never now if a return bloom is same or different since many blooming algae appear much alike to novices without microscopic examination.
Let us know how it works.
Last edited by Bill Cody; 09/15/13 08:32 PM.
