ATO failsafe design, need help!

[The Reef Addict]

Hello reef community,

As the title states, I am looking for advice on a failsafe ATO design. Ive had reef tanks for 5-10 years now, and I recently got my first ATO and I love it. But I still have a hard time trusting it (along with the direct top off solenoid that comes with it) given the accidents I've had in the past.

I purchased the "Ultimate ATO"

https://www.bulkreefsupply.com/ultimate-ato-4-sensor-auto-top-off-system-xp-aqua.html

Right now I'm not using the solenoid at all, given my slighly paranoid state about flooding my new-to-me house. I will be moving my tank here soon and want a bulletproof setup for convenience and reliability. I will likely be running a line up through the basement floor from my RO/DI, If I can I would love be able to run a line directly to my sump.. But again reliability is a must.

As of right now, I fill a 10g top off tank up (manually) with a pump/siphon break combo to my sump thats tied into my ATO. So beyond filling the 10g tank, its a brainless operation.. But all it takes is clumsiness to accidentally overfill the top off tank.. Then my soon to be wife will kill me. Lol

Please - help and suggestions!!!

[tkeracer619]

Using an RODI to directly fill a sump is bad for the RODI system. Short cycling increases TDS and burns through DI.

You should fill a storage tank or container of some kind. Preferably 10 or more gallons at a time. Many people use brute trash cans or poly tanks. I assume this is what you are talking about when you say (top off tank) and that the solenoid operates the RODI.

Then you top off the tank from that.

To bulletproof and RODI, use a float valve and a ASOV to shut down the RODI in case the solenoid valve fails. Use another float switch on your sump that will shut the system down should the optical sensors fail. I prefer autotopoff.com longwire setup. You choose a controller with x many floats and then pick the type of floats you want. It's a great setup.