Here's mine
2 40 gallon Brutes, 2 150W heaters, 1 powerhead and a Mag 24 to tie it all together. Also use a 5 stage BRS RO/DI with an upgraded 150 GPD membrane.
Plumbed directly into my tank/ato upstairs. Probably the best thing I have done yet. Actually makes water changes fun!
You can see here where it goes left into the water change sump, or right into my ATO resevoir
I usually leave all the valves set so that I can just flick a switch upstairs and it fills my ato resevoir. When I want to do a water change, I just divert all the valves from the saltwater mixing barrel on the left. Best thing I did was run an extension cord up to my American DJ powerbar for the water change pump. After everything is set up downstairs, I just go upstairs, and turn the pump on.
Im working on a video that outlines how I do a water change. But I also have a video in my tank journal that shows me topping up the ATO resevoir if you want to check it out.