A couple days ago I set up a 65 gallon planted tank (see previous post / two away) I bought the tank used and it came with a 110 AquaClear, which has a high 300 gph rating. It really churns the water, especially at the surface; should I be concerned about that. I don't inject any CO2 I only use Flourish Excel for a low tech tank, so I'm thinking I don't need to be concerned about gassing off the CO2. I might raise the water level in the tank some so the action at the surface is not so much like Niagra Falls. I've also considered replacing the 110 with something smaller like an Aquaclear 70. Note: There is also a Eheim 2215 running on that tank. I've considered running two Eheim canisters, one vertically and one horizontally, in place of the HOB filter. Any thoughts or suggestions?