Thanks on the advice on the sump...however I do not believe that would fit my sump. I have the model 4 high capacity sump made by marinedland and the ASM G2 protein skimmer fits just right. But when i add more fish I am afraid this skimmer is not going to be enough so I need to find something with dimensions similar to that of the GS. I noticed marineland makes an in the sump portein skimmer for the 300 gallon but I can not find any reviews on it. Thanks!!!