LED's seem great, but I've always loved T5 and MH technologies.  This tank is now a mixed reef so I have to be kind to my LPS as well as giving light to the SPS that grew from the previous encrusted parts that stuck around.  Over my 75G tank I have 4x54W T5 HO bulbs.  I'm now using the Tek T5 retro with the reflectors, below is the par readings with a few light setups, check out the 4T5 one for the current state.  I'm running the lights 10 hours a day full power, with 2 hours of just one bank of two.

I use a 29G sump, but to keep things quiet I have a return of only 60GPH.  This will turn over the real water volume about once per hour.  I use a filter sock, I do this to try and raise NO3 which had always been 0, I also dose NO3 weekly to achieve a level above 0.  I find having NO3 has naturally suppressed P04 numbers.  The sump is basic, I use a Bubble Magnus Curve 5 running dry enough that it needs the cup emptied about once per week, and I have 1/4 cup Po4 remover in a mesh bag inside the sock which is replaced monthly.  I have an Ehiem pump for return and I monitor flow with the Apex.  This is great because I can kill things like the heater if flow drops below 5gph for some reason, that way I don't cook the sump because my return failed.

I like to target NO3 levels of 1, and PO4 below 0.1, I'm finding my PO4 value is usually 0.04 which is a touch low for this tank, but I enjoy only cleaning the glass every 4 days so I'm hesitant to change my methods.  

Now that some of my SPS are starting to come back, Kalk is simply not keeping up.  I just bought the DOS with the DDR from Neptune and I'm finding that I love it so far!  It's super easy to use, and way more accurate than dosing pumps of the past.  Plus I don't need to do math to figure out how many seconds equal 1 ML and all that.  I'm using Randy's Two-Part.  The formula that raises PH.

My sump used to have a Cheato fuge, now that has some anthelia in it that was getting too aggressive in the main tank.  I also plan to keep xenia down there and any other soft corals that come out of the main tank.  I have a small propellor pump down there for flow since the flow through the sump is so low.

Even with modest lighting, small pumps, and not many other things to add heat to the tank I need some cooling toward the end of the day.   Now that the tank is in my office the humidity with the doors closed and fans for cooling became a huge problem.  I share a wall with the garage, so I plumbed a 1/10 HP chiller through into there and it's doing a great job.  Plus with it being in the garage it keeps the heat and noise out of the house.