The tank I'm running right now is a custom shallow 50g 16x16x48. I'm running about as bare bones a system as possible and have some great growth so far, it's only had coral about two months. I run a return pump, 4 bulb t5 Hamilton fixture, small skimz skimmer, 4" body probably rated75-100g, and really it's almost just an ozone reactor for my $100 spa ozone generator. And an algae turf scrubber. Now I do run a m1 vectors return and run about 15x tank vol through the sump, and have two mp10 vortechs, and two tunze nano streams. So it's about $2k in the setup. And then an apex.
Yea it's a bit overkill for a 50g but I run <1ppm no3 and 0.03 po4. It runs on an auto feeder and if it weren't for adding water I could walk away from it for two weeks and it will be fine, in fact I already have gone on two week long trips. Now I do build large custom tanks for a living so the whole idea was to not deal with all these additives adjustments and what not because the last thing I want to do when I get home is more tank work... So I run no gfo, no carbon and only dose Randy's 2 part, and still haven't done a single water change. It's setup a bit complex and it's taken 8 years experience to get back to a natural reef, but I find it much more relaxing when I dose as few additives as possible and go more au naturale.