The Tunze ATO on my setup quit working. The pump and float switch are fine. It's the circuit board, and it just constantly clicks. I need a new ATO as soon as possible. There are so many mixed reviews on all them. I'm sure it will be the same on this post as well, but I wanted to see if there would be a clear winner. I have a 90 gallon with a 29 gallon sump. What would you all suggest?
Best ATO
- Thread starter Sully32
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BlennyTime
Well-Known Member
I used a bucket of water, a pump and a float switch for a while. The pump runs into the float switch and keeps the level constant. It was about $30 to set up
MONTANTK
Valuable Member
They might be under the Eheim brand now but they’re not super common. The technology though is very simply which limits the points of failure. It’s essentially a black tube which measures barometric pressure and when it drops below the tube it fills the water halfway up the tube again
Greybeard
2500 Club Member
Sure
I don't use an ATO reservoir, so let's start with incoming water. I'm going to ignore non-ATO related bits... the RO/DI line feeds more than just the ATO. It's not as complex as it might seem.
RO/DI flows through an electric ball valve
(hm.. why is it I can't post a URL to Amazon without cutting off the protocol header?)
www.amazon.com/Motorized-Valve-Stainless-U-S-Solid/dp/B06XXPZHVB
From the ball valve, the RO/DI water flows to a mechanical float valve, mounted in the sump. Water reaches the level of the float valve, it closes. Water level drops, it opens. Simple, easy, mostly reliable. Yes, float valves will fail... that's why it's backed up with the ball valve. So far, I haven't had a problem, but I do change out the float valve every other year. It's a few bucks, takes maybe 10 minutes... why not swap it out regularly?
Mounted just above the mechanical float valve is a float switch. If the float valve fails, allowing too much water into the sump, the float switch is tripped, which cuts power to the ball valve, shutting off the incoming water. Since this switch is normally high and dry, there is very little chance it's going to fail. Also, my normal weekly water changes cause the water level in the sump to exceed this level... so I get an alarm every time I do a water change. Kind of a built in weekly self test
Direct wiring this sort of circuit isn't difficult. 12v power supply running through a NC float switch, powering the ball valve. Float switch is tripped, opening the circuit, dropping power to the ball valve, which closes. I used this kind of solution for many years without issue.
Worked fine... but I eventually started using an Apex. Sump HI level sensor rewired to the Apex breakout box, and the 12v power supply for the ball valve is plugged into a controlled outlet. Sump HI trips, Apex shuts off the ball valve, ALARMS, and emails me an alert.
With the Apex, I can turn the ball valve off, and alarm, if my leak detector in the sump room floor goes off, or if my Kalkwasser reservoir level goes above normal, or if my saltwater mixing station water level goes above normal. Also of note, since the ball valve closes on power loss, if the house power or a breaker goes off, incoming water is immediately shut off. Sure helps me sleep better at night
Oh, I'm likely to get called out here by someone about RO/DI TDS Creep. Using an RO/DI unit in short bursts can cause TDS creep, with more 'stuff' getting through the filter, causing excessive DI consumption. They're not wrong... but, it's not a problem in my case. The same RO system feeds my household drinking water faucet, chilled water in my fridge, both of my ice makers... We use LOTS of RO water. The unit gets plenty of exercise. TDS coming out of the membrane is never > 4 ppm.
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