I would only use a bio-wheel filter on a low-light, hardy plant setup. If you are not looking for any kind of real growth, and just want simple plants like Java Moss, and Java Fern, and other low maintenance plants, you can still have a lovely, perfectly functional tank. If you are trying to keep some CO2 in the tank, change the filter out. I noticed a drastic change in CO2 loss using a bio wheel filter (Penguin 125) vs another normal HOB filter. You can save some CO2 by ditching the bio-wheel and just using it as a standard HOB filter. You can save even more by using a canister and the like!
It can definately be done, but Emperor and Penguin (and any bio-wheel) filters are just not very efficient for use with planted tanks. Hang-on-back filters, in general, follow suit behind them, even with water levels kept at the lip of the aquarim, although they do work quite a bit better. This is just my opinion based on my experience, and it seems many others have had similar experiences. See what works for your tastes.
It can definately be done, but Emperor and Penguin (and any bio-wheel) filters are just not very efficient for use with planted tanks. Hang-on-back filters, in general, follow suit behind them, even with water levels kept at the lip of the aquarim, although they do work quite a bit better. This is just my opinion based on my experience, and it seems many others have had similar experiences. See what works for your tastes.
