Join Date: Jul 2010
Location: Outside Philadelphia, PA
In my opinion, unless your willing to drill the tanks, and install bulkhead fittings, and connect them, using a single canister filter on two tanks is looking for trouble.
You need a way to keep the water level the same in both tanks. While it is possible to use a siphon between the tanks, if it fails, you have a major flood, because the canister will pump one tank dry and the other will overflow.
That's also a lot of work for two 10 gal tanks. I'd go with two hang on the back filterers or two canisters, if you want to spend the money.