The AquaFuge comes standard with a Rio 400, which is rated at 189GPH. I would recommend going with a MaxiJet 600 as a replacement: which is rated fairly close at 160GPH.
For the MaxiJet installation, you will need a short length of vinyl tubing (1/2" I.D. if I recall correctly) along with a couple of hose clamps.
Please let us know if you have any further questions.
Sincerely,
Joseph
Marine Depot Customer Service