For water changes I have a 90 gal. in the basement plumbed to mix and pump up to my display upstairs.
I put in 3 way switches so I can go downstairs shut off the pump reverse gate valves and go to the display and turn the pump on to fill the sump. I drain the sump into buckets still (for now) so I can vacuum it out.
It then refills with a float valve to the RO/DI. I am still tweeking the system but so far I like it.
i use a aquahub.com ATO its a DIY one works great. for my RO i use a trash can and a kent RO ATO. i dont have a salt changing system other then by hand.