Kyle,
Don't have experience with returns and related pumps, so I can't help you there.
However, everything I've read about seagrasses and zoos is that you're going to need serious MH lighting for these to thrive.
If I were setting up a new SH/pipe tank, I would go with a standard 24" long footprint and throw on some PC lighting. You could make the tank as wide as you want to accommodate the amount of lighing you think you will need for the inhabitants other than the SHs/pipes. SHs don't need lots of light, ime. The tank could still be 30" high for mating purposes of larger SHs.
One caution about breeding SHs: once they get going, you will have fry every 2 weeks or so. Rearing fry and raising the right sized foods for each brood of fry can be an all-consuming task all in itself. Have done this for 3 broods of fry, unsuccessfully, and I was a wreck from all the work
However, larger SHs, such as H. kuda or H. reidi, are typically not available in Canada except as wild caught, which can sometimes be very tricky to train them to eat frozen. Here is the SH Feeding Station Gallery for you to read through to get ideas of how to train WC to eat frozen:
http://www.lostmymarblz.com/hh-feeding-stations.htm
Here are two Canadian suppliers of captive bred SHs:
http://www.seanic.ca
http://www.aquaparadice.com/
HTH
