I recently set up a 33 gallon shell dweller tank. I have noticed that the two Aquaclear filters are doing a nice job of keeping the water clean, but I don't have as much surface agitation as I'd like to see. I have also noticed that there is good circulation across the front of the tank but there is less flow across the back side. I was thinking about either using one Hydor Korilia nano 425 in a rear corner aligned along the back wall of the aquarium or 2 nano 240s in opposite front and rear corners to create a circular flow. I'm not opposed to using two 425s but I'm concerned this may be too much current. Has anyone ever used a circulation pump such as the hydor korilia nano for this application? Would you recommend this type of current in a shellie tank? Would it be good or bad for them? If you would use this type of circulation pump, would you use one across the back or smaller pumps in opposing corners? Is the Hydor Korilia a good pump or is another brand better? I know I have posed a-lot of questions. Thanks in advance for sharing any thoughts you have.