What brand and model pump will you be using as the return from the sump?
I think you will have difficulty controlling the volume of water added to the 3 different tanks using one pump.
I also wouldn't recommend using a separate pump to return water to or from a canister filter unless you aren't using that canister filter with a power source.
What brand/model canister filter is it?
Eheim Pimpette #270
Eheim Pro II 2028; Classics Series -2215, 2217, 2260, 2262; Pro 2229 Wet/Dry