Hello all,

Currently trying to set up an AWC on the 500 gallon display in my store. I have set up the new apex system and it's working great so far (especially love the new heartbeat feature, saved me already).
So far, I have installed a DOS and a breakout box with 2 switches on the top and bottom of a barrel. I have RODI water that is gravity fed down to a float valve in my sump. What I want to do is split the RODI supply and install a solenoid that will control when my barrel is getting filled by RODI, but will only fill up once it is completely empty.

So, I would like for my solenoid open, fill the barrel with RODI on tuesday and stop when it hits the top switch, then I want my DOS to remove 40 gallons from the aquarium, while replacing 40 gallons from the drum on thursday. Then when the switch at the bottom of the barrel is triggered, the solenoid to open and fill the barrel back up.

I think this is a good idea? If anyone can give me some suggestions, guidance, or even ways to improve this, I would greatly appreciate it!
Thanks!