Top off water is RO/DI collected in 2 x 44 gallon Brute cans (plumbed together).
It is mixed with limewater in 3 x 44 gallon Brute cans (plumbed together), and pumped to the tank with a Reef Filler pump on a big float switch in the sump.
New salt water is mixed in 2 x 44 gallon Brute cans (plumbed together). I use Instant Ocean, and add to each batch about 100-150 ppm of magnesium (I don't measure it, I just add about the same amount each time). I maintain the tank at ~35 ppt (sg ~ 1.0264).
I use the new salt water for automated water changes using a dual head Reef Filler pump on a time so it changes about 1% daily spread over many 15 minute periods of the day. I mix the salt water for about 24 h then turn off the powerhead (unless I forget :D ) and let it sit unstirred. I never heat the new salt water, except in emergency need of a lot of water. The old water is sent down a basement sink drain.
Temperature is controlled with a whole bunch of ordinary heaters on two Dynasense temperature controllers.
In the summer, the water is cooled by sending cold tap water through a big coil of plastic tubing int he sump, and then out tot he yard to water plants. The flow is controlled by a solenoid connected to one of the temperature controllers.
Water coming down to the basement from the main tank enters the first of three 44 gallon Brute can refugia, at the bottom. It rises through mostly live rock with macroalgae growing in the top 2-10% of open space. The water leaves that can and enters the bottom of a second, essentially identical can. Water leaves that second can and enters the first 44 gallon Brute can of the sump (yes, I like Brute cans :D).
In the first section fo the sump is the cooling coil, the skimmer inlet and outlet, a canister inlet and outlet, and another refugium inlet and outlet.
The skimmer is a ETS gemini 800 on an Iwaki 55RLT.
The canister I won at a MACNA raffle (along with a lot of other stuff) and it is filled with a mix of ROX GAC (from BRS) and GFO (from BRS).
The third refugium is mostly identical to the other two, but with less live rock (about 12-18" open water at the top with Caulerpa racemosa). It is fed by a powerhead and drains back tot he first sump section.
The second sump (44 gallon rute can) gets water from the first sump section. It has the heaters and temperature sensors for the temperature controller, and the outlet to the return pumps (two x Iwaki 40RLXT in series) that send water back upstairs to the main tank.
