Have decided a 2nd time for this product, thinking that I might have done something wrong the first time, maybe my pond is yes but bigger and the dosage was too weak. Did the treatment so carried out again, initially abgekechert algae manually and cleaned the pond, about 4 hours of manual labor, then exchanged water over another 4 hours completely, that is pumped pond, filled with the same fresh water / ground water from the pump. The pond water was clear then - logically! After Algosol applied. The next day, the pond water was still clear, fine, but just one day later showed the first downturn. From day to day it was cloudy. Imer again abgekechert algae. After three weeks, once Algosol applied. Today, after 8 weeks since the first application I have another green soup !!! If it is not at the center, it is perhaps the pond itself (vegetation, fish population, lack of shade ???) I'm not an expert for that matter, it is clear only Algosol was not helpful.