I am sorry, but like shellsea's wife, I am "not feeling' reading 1800 posts about mixing stations. But felt I should share one concept which I love and likely would not be added until the 2500 mark or so. I plumbed my SW tank into the system with a valve so I can take it out of the system whenever I want. Which is INVALUABLE. The SW mixing tank is a bit higher than my sump and has a small pump [which also manifolds into several reactors, fuge and frag tank]. I have another small pump which recirculates water through the SW tank but also has a T with a valve and a segment of loose flex PVC [long enough to reach the sump] and a T-valve into the drain. A 2nd small pump is attached to the RODI reservoir. The SW mixing tank has one of my heaters in it permanently. When it is time for a water change: 1) I close the valve to the SW mixing tank isolating it from the sump, 2) I open the valve to the drain and drain it [actively pumped by the mixing pump], 3) I activate the pump from the RODI reservoir to fill the SW mixing tank [this pump is on my neptune apex and also auto-flushes my skimmer twice daily], 4) I add salt and wait 24h to both confirm the S.G. and wait for then water to warm, 5) then I open the SW mixing tank to my main system [which adds 10% more volume to the total system and therefore increases my systems' stability]. The crown jewel of the system, however, is that when I need emergency water [which should be never be the case but, shockingly, proves bi-annual or so], I can simply close off my SW mixing tank, and use its pump to pump IDENTICAL WATER [completely matched for temp, salinity, and all parameters] directly to the sump. The latter has saved my butt numerous times. If you have the space and can ensure that it is somewhat protected from major environmental temp swings, this system is highly, highly, highly recommended. $0.02.