I appreciate all who have taken the time to share their WC setups, the different designs and ideas were a big help when I finally decided to build mine. I hope this post can help someone who's been thinking of building their own. Here's mine.. hope it makes sense
Two 40gal poly tanks. RO/DI fills the top tank in the pic and also a 7gal ATO reservoir that's under the tank next to the sump.. both are connected to the same RO/DI unit with a T fitting. When the ATO tank in the house is full it stops flow via mechanical float, then water runs to the top tank in the garage which also has a float valve installed. Apex controls a solenoid that turns the RO/DI on once a day.. an hour seems to be enough to fill the ATO and usually give the WC tank 2-3 gallons or so. Also have leak sensors connected to the Apex that are next to the ATO, RO/DI unit, and tank in the garage.. it'll shut down the solenoid if water is detected and also send me a text message. After 10-14 days I have enough fresh water (top tank) for a water change. Just open a couple valves and the water fills the salt tank on the bottom which has a heater, powerhead, and temp gauge. I usually always have 35 gallons mixed and ready to go..
I've been carrying 5gal buckets of water for years and was finally tired of it.. so I made this. I turn off the return pump, skimmer, ATO, and couple reactors but leave all powerheads in the DT tank on.
After the DT has stopped draining into the sump, I mark the water level (very important) with an erasable marker on the sump. Then drop this pump into the sump and run the hose out a window to my backyard.
When I've drained enough I turn the pump off, but leave it in the sump. I grab the end of hose that's outside and connect it to the WC station.. this is why I installed female connectors (both made of plastic) on both ends of the hose. I open a couple valves, turn the WC pump on, fill the sump back up to my water level mark made earlier with marker and the WC is done. Turn everything back on, pull the pump out of the sump, roll up the hose, flush with fresh water for storage and that's it