Join Date: Jan 2008
HOB filters are fine, depending on what you are doing.
For example, if you are injecting CO2, you will want to minimize the amount of surface disruption there is, so a HOB filter may not be the best choice (the filter return waterfall creates quite a bit of surface disruption).
In addition, the biowheel adds more surface area, allowing CO2 to off gas faster.
Of course, this is not really a problem if you are not planning to inject CO2.