hagen boimax filter meduim, any use in a 20G tank?

Hi, just wondering if using biomax in a fluval 2 internal canister filter is any use on a small 20 gallon tank? the filter comes with foam pads and a carbon insert as standard and i was thinking i could replace one foam pad with the ceramic beads. Its a new tank too, no started to cycle yet, so is it better to start off with the biomax, or replace it later on after the cycle has started (while keeping one of the cycled foam pads)

any tips greatly appreciated :bowing:

Alex