I am trying to work which Fluval canister would be best for my aquarium needs ? I am currently setting up a 112Gl (450lt)heavily planted tank with shoals of tetras and several discus. I note the fluval 405 would be at its limit and was wondering if I should rather go for the FX 5, as I plan within the next year or so to perhaps upgrade to a bigger tank closer to 175 Gl. The larger size of the Fx5 canister would presumably create better bilogical filtration than the 405 and I note there are some other advantages. However I trust thewaterfow of the FX 5 would be too much for the tank and the plants, and limit the Co2 with such a hight flow rate. Can I reduce the flow rate without harming the motor ? There is not a substantial cost difference between both models, so was wondering if the FX5 would be the better long term option ? I would be most grateful for your wisdom on this ?