On Sunday I bought an AquaClear 70 (300 gph) for my 20 gallon tank. If you check some of my recent posts you'll see I only had a UGF before and am now adding a good filter. I think the flow from the filter is too strong in the tank. I worked from home today and had lots of time to observe the tank and I really think the current is too strong. Tonight while doing a water change and having the power filter and UGF powerhead shut down I really saw how much the fish are struggling. I think I'm going to drop down to the aquaclear 50 (200 gph) and shelve the 70 for my developing MTS ;D Since I've been running this filter just 3 days I could start completely fresh but I think I may just cut down the sponge media from the 70 to fit the 50 and use the bio-cubes from the 70 as well. I've read that the carbon really only works for about a day and after that it's only good for accumulating bacteria. Depending on the size difference of the carbon media I might go with the new carbon so there's room to add some Nitra-Zorb media to address my nitrate problem. Does anyone see any flaws to this plan?