Yes this will work, I have used a setup with 3 canister filters on the same intake/output for years.
I have 3 Magnum 350 filters with a combined 1" intake and 3/4" output with 3 "nozzles" on it. I only run 2 filters at a time on timers, for all 3 you'd probably want slightly larger hoses.
Its not necesarry, but a good idea to have the intake larger than the output. I went with a slightly undersized output for a higher output pressure since I'm trying to simulate a river biotope.
Tube Size | cross section | max flow rate (approx)
1/2".................. .195" ................. 200gph
5/8" ................. .301" ................. 300gph
3/4" ................. .442" ................. 450gph
1" .................... .785 .................. 800gph
1.25"................ 1.227..................1300gph
1.5".................. 1.767..................1900gph
2.0"...................3.142..................3500gph
These numbers aren't set in stone... just some rough estimates based on what I've read, and looking at hose sizes that manufacturers use.
Here's my current setup:
Overall I'm happy with the setup. If I could do it again I'd probably go with a sump.
Regarding different pump/filters with different flow rates, I haven't noticed any issues with this. Perhaps theoretically if you had one pump that was much much stronger than another, it could create enough pressure on the output of the weaker pump that it wouldn't get through, but I haven't noticed this effect.
Right now I have a small circulation pump that I don't usually run, I intended it to run a reactor or heater or something which I I'm not currently using. It has less than half the flow of the magnum 350's when they're clean. Or for that matter the magnum 350 pumps have significantly different flow depending on the filter type and how clean it is. I've only noticed that the flows seem to add up to each other, their flow rates don't seem to interfere with the other pumps to a noticeable amount. Your results may vary.