05-24-2004, 05:51 PM
Join Date: Jan 2004
Location: Dallas, TX
iTrader Positive Rating: 100%
All canister filter are rated "at the pump". They don't take into an account the hydrostatic head provided by the hose leading to the tank. Some manufacturers include a little graph showing the flow at different heights.
A big Eheim, rated at 315 gph. would barely move more than 110 -120 gph. if the end of the outlet hose is 5 ft. higher than the pump.
With a heavily planted tank you will probably not have problems with the biological filtration. If the bacteria does not get to all the Ammonia the plants will (providing they have good light and CO2).
Lack of circulation could be a problem though - because of the thickness of the plants you may have uneven heat distribution. Touch the glass of your tank in several places with your hand to make sure the temperature is good.