Gang@Ukaps According to nemerous articles or threads on this forum and other forums - poor or insufficent water flow / circulation assist or cause algae to become abundant within the tank. So he is my question ? - why is it where ever I point the oulet water pipe (flow at max output) algae becomes abundant and thieves, this is directly infront of where the flow is going. Answers on a post card please - one for the pro's / experts to answer. Regards paul.