I have been neglecting my tank due to many problems that have come up. One thing I've been having trouble with is my skimmer. I have a CPR Dual Bak Pak and it was working great and producing about a cup of green sludge every three days. Now it hasn't even produced that in a full month or two. I've heard that people normally replace the pumps on the CPRs. Does anyone have experience of which pumps I could put on it instead or any other suggestions to get it to pull out more stuff? I've taken it off and cleaned it all out with hot water multiple times but I think the pumps are shot and I don't want to buy something that won't work well.