In pond products, it is often the case that they are tilted in the pond water and then waits to see an improvement. For me it was so that after a medication used in the koi pond I had problems with the nitrite values. The Koi have hardly accepted food. So it was to act hastily. Through the drugs in the filter micro-organisms were probably badly affected and these are reducing the nitrite. So I dosed according to the filter starter bacteria from Soll to instructions. After 3 days I was able to see an improvement on the basis of water measurements. After a week, the water levels were top again, the Koi resumed feeding on itself. Now I set the filter starter bacteria always in the spring to start a filter and have a Reserver home, if the values should not vote again. Good product and also to recommend pricewise.