I feel for you man I did that earlier this month too. Some of the zoos in that tank are coming back but so far none of the mushrooms have came back
all the fish seem to be rebounding nicely now I just have to contend with a cyno bloom. Keep positive that your corals will come back. My top off system as I use it for multiple tanks scattered around the house is simply a 1/4" line that I drag to the appropriate tank and open the valve and the ro unit turns on and stays on till I close the valve again. Simple but very risky we are retro fitting the system with a pair of solenoid valves rigged to a timer that will open them for a user set time period then close them after that amount of time. And to keep from relying on the valves to work to shut things down it will have a stand alone manualy cleared timer as well to make it hard to ignore/ forget about.