2 Mini Canisters For A 20Gallon?

[mwood2]

Well I am working on my next project of a 20G Long DP tank. Since DP don't like currents a whole lot I chose a mini canister filter that includes a spray bar. The canister I chose was the Zoo Med Turtle Canister Filter 501. Its works great on regular tanks from what I have seen in the past day and the current is low as to not push the DP but what I curious about is if I should have 2 or 1 on the tank. Its rated for 70GPH and around 15 gallons (it says 30 but the company says that a 30 gallon half filled tank for turtles). I also plan to add a sponge filter too to add to the filtration. Its 35 bucks for another which isn't out of my budget, so would it be worth it?

 

[Skins]

I have in the past been advised to get a filter that will cycle your tank at least 4 times per hour and if its planted even more.
So imo i would have two running with one of the filters return flow nozzle pointing at the glass, this will keep your overall flow in the tank down.

Keith.