I flirted with tank crash for a month or two when I had inadequate surface agitation as well as uneven C02 distribution. Now, I have a spray bar that runs along one end of the tank, aimed the length of the tank and upward as well as a smaller powerhead aimed upward and towards the opposite corner of the tank to help push the flow along. It essentially pushes the water in a large loop down the length of the tank and I was surprised to see how much better the C02 flowed throughout the entire aquarium. It also allows you to crank up your C02 as well. More oxygen in the water means that more C02 can be pumped into the tank.