On the 55G it is just an Algae Scrubber and occasionally I toss a small mesh bag of a mix of rox carbon and GFO in the overflow box. Mag5 return pump, jager heater, rio pump for scrubber, and an old Koralia 3 in the display for flow. Lighting is DIY 24 LEDs 50/50 mix of RB/CW Crees.
The only difference from the day I set it up is I just last week replaced the CFL bulbs with PAR 38 Grow LEDs (red/blue) on the scrubber and I can already tell they are making a positive difference growing algae on the screen. No dosing, very few water changes (I think 3 small ones since it has been setup), no real testing (mainly just look at corals and gauge tank by that), manual top offs every couple days, usually 2-3 gallons at a time (so I am not good at maintaining steady salinity), and it is still one of the most stable / ultra-low maintenance tanks I have ever setup. My 75G has crashed a few times from doing experiments and each time I have to move my SPS corals into the 55G in order to save them. I would be surprised if I have spent over $500 total on the 55G tank to date. This tank has the clownfish that have babies every 14 days and I have had corals spawn multiple times now, both anemones and SPS corals.
The 55G is the tank that is not supposed to work according to the 'know it alls', at least in my area. I am not supposed to be able to grow SPS corals with only 24 LEDs on a 4' tank, especially on the sandbed when the lights are mounted 18" above the tank, but I do. I break every rule in filtration, flow, and lighting, and yet it works fantastic and best of all, CHEAP.