I agree with Rainman that the under gravel is not the most efficient system. But Robbor said he only wanted to run a pump for a few hours a day. I would be concerned with losing the beneficial bacteria with a bio wheel or a wet dry filter because of drying out when not being run continuously.
Do those sand filters help address the nitrate levels some how (I am unfamiliar with them)?
Or is the level of ammonia produced reduced due to the fact that there is less debris(food and crap)trapped in the gravel?
