I have a 30gallon tank with 8 cichlids in it currently. They all seem healthy and happy but my friend is telling me that they need a bio-wheel filter. I'm currently using the normal filter that came with the tank and it seems to be doing fine. The water is very clear, Ammonia, Nitrate, and Nitrite levels are all 0, and the fish are all active. So my question is, Is it worth it to invest in a bio-wheel, or will my fish be fine with the filter I have now?