Is the peat moss just to lower the pH of the tank? If so, maybe you can place the peat moss in a media bag and place it in the filter, so as not to clog it.
As far as a canister filter, maybe look at an XP3 or Eheim Pro II 2028/2128. If you don't want to place the peat moss in the canister, just place a sponge over the intake.
As far as a canister filter, maybe look at an XP3 or Eheim Pro II 2028/2128. If you don't want to place the peat moss in the canister, just place a sponge over the intake.