I got an Octo NW200, but it came with no paper work except a diagram showing how to put it together. I have had it running in my sump for a week and I can"t get it to put any skimmate out. I have lifted the output tube, but it either falls back down or something. The foam starts to rise then the next time I look it is down again. I really need it to put impurities out of the water.