Two tanks, one filter?

[coldmachineUK]

Hi, the idea of sumps confuses me: can a sump be used to run two tanks off one filter? I'm talking FW setups here, rather than SW.

Basically my problem is this: I have a new 30G and a new 20G, and I'd like to run both of them off one filter setup. Is this possible?

[Toirtis]

Possible, but complicated, inadvisable (a common filter means that any disease introduced to one tank will affect both tanks within minutes), and likely just as expensive as having two filters.

[mvigor]

I have two rubbermaid growout tubs bridged together with PVC pipe and filtered together.