RBC--Glad to hear you're making some progress, but it's not suprising that you didn't achieve any balance just by killing algae. When you killed the algae, its rapid decomposition added a massive amount of nutrient (decaying biomass) to the water column, and it seems logical that it is now feeding whatever is growing in your green band. I would not add more copper sulfate (by the way, did you end up using a chelated product like Cutrine?), but this would be an excellent time to initiate some kind of microbe treatment (see the current thread on this subject). The microbes chow down on those free nutrients and deprive the algae of them. It would also be a good time to dose the pond with Aqua Shade. I'm not sure that a CuSO4 treatment would have any impact on microscopic suspended algae (for some reason, our pond has never had that particular affliction), but I'm sure someone here can help you with that. For what it's worth, I was at Tractor Supply this morning and they are carrying both Cutrine Plus and Aqua Shade, as well as competing and cheaper brands; as others have pointed out, the competing and cheaper colorant has blue dye only, while A.S. includes a yellow dye and so affects more of the spectrum.
