Sorry for the delay my microwave connection just returned.
Yes this is my only filtration although I am considering replacing the cartridge filters with two FX5's.
I am lucky in that my well water Ph and Hardness are perfect for Mbuna.
I'm interested in hearing your thoughts on why a UGF is not an option.
Is there an advantage to sand versus gravel ?
Sand is a lot more work than gravel. It really looks cool, but you have to periodically stir it to avoid anaerobic activity. Plus sand can get in your algae scrapers and scratch the tank.. Gravel is easier to vacuum. Gravel is much better, esp in a big tank. I'm never doing sand again, unless I keep something that really needs it.
IMHO, you don't need a "cleaning crew", just vacuum the substrate once a week. There is nothing wrong with your UGF, your UGF is probably the best out there....I use them in half my tanks. I would advocate either a FX-5 or a couple of HOB's to add to the filtration.
The tank looks great, maybe a little more aquascaping....your fish look very healthy!