I wouldn't say HOBs are 'bad', just less suitable for planted tanks. I use HOBs on my small tanks, and need to use more CO2 to achieve the same results I get on my 65g, where I use a canister. Bio-wheels definitely cause you to lose more CO2 than other HOBs - I just removed the wheel from my Penguin 170 and without changing anything else the CO2 in the tank went from ~12ppm to ~20ppm. I find it's helpful to keep the water level as high as possible so the surface rolls but there's no splashing from the outflow.