Hi Nathan.. thanks! I really love this tank. Like you, I feel that corals are.. blah blah blah.. interesting, but nothing like the feeling of exploring a new tangent in this hobby. The grass has been a fun new challenge.
For filtration, really only water movement. I had a single aquaclear powerhead on the tank as a ten gallon, with the twenty gallon there are two of them. Filtration in the real sense is a quickfilter attachment with some fine 100micron filter pads whenever I need to suck some algae out of the tank. I clean about once every two weeks or so.. just a glass scrape and clean some of the non-live surfaces in the tank. I run lots of aeration via a super cheap skimmer just to help out with pH balance. Its not uncommon for me to have high pH readings due to the plants pulling dissolved carbon dioxide out of solution. Aeration takes care of it.
I think aeration and the lights.. about 96W over a ten gallon.. are far more important than just the filtration. As is providing nutrients to the plants, via organic supplementation in the substrate.. and water column dosing of fertilizers while I'm running a fishless tank.
If you run a macroalgae only tank.. a good bit of this can be ignored. Lights for example, may not need to be so intense (though I'm not sure) and I dont know if they pull carbon dioxide from the water.. they may pull their carbon from the alkalinity in the tank instead. I'm not sure, but you may not have such a pH headache. There are others on this board that should be able to give you a much better idea. I've been focused on the grasses needs way more than some of the macro's.
For sources of grass in Kansas, there's billsreef, Floridapets and Gulf Coast... though I dont know if I can recommend Gulf Coast right now. (I tried to order a week ago and havent heard diddly from them.. its sad, because they were SO great on previous orders.) Manatee grass is rumored to be the best beginner's grass.. though I've had the most luck with shoal grass so far, and the turtlegrass is settling in very well.
I hope that helps.. any other q's or thoughts just post away!
>Sarah