I have been advised to aerate my tank since day 1 of planting my first plant. But never know that the it's called aeration. I aerate by tank with an air stone after an hour of timer setting after the light and Co2 are off. It will also timed an hour to off before the lights and Co2 are back on again. It was adviced by the local lfs (88 sunwaymas). So far algae has surfaced but manage to control the growth of algae. The main purpose is what mentioned by stan to help aerobic bacteria to consume organic debris to maintain a good health aquarium.