Oh i remember the garden centre guy saying the clarifier can be fitted to the top of the filter which is what I have donw. I was going to move the clarifier after the filter but realised from the filter to the pond is gravity fed, and the pond to filter is pump fed. If I moved the clarifier it would have to be below the filter and be gravity fed and I dont have room for that so will leave it where it is and see if it works.