My ATO:
Apex
breakout box
digital aquatics float switch
Tom's aqualifter pump

The program turns on the ATO every ~4 hours and replaces what has evaporated. It typically runs for 5-10 minutes, with a check for the return pump and salinity. Worst case scenario my entire reservoir slowly empties into my sump causing 3 ppm salinity drop. No flood, my sump is big enough.

[SumpATO_A8] (virtual outlet for switch)
Fallback OFF
Set OFF
If Sw1 OPEN Then ON
Defer 001:00 Then ON
Min Time 240:00 Then OFF
If Outlet RTNPUMP_4_2 = OFF Then OFF
If Condx5 < 33.0 Then OFF

[ATO_4_4] (aqualifter outlet)
Fallback OFF
Set OFF
If Outlet SumpATO_A8 = ON Then ON

I just build my own digital one with dual optical sensors for extra reliability
http://images.tapatalk-cdn.com/15/07...0cfc6a9ea9.jpg


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Where do you get those optical sensors I used one of those before and found them very reliable.

i'm shocked the tunze pump has failed for you like that. i never let mine run dry which i think is the key and all the ones i've run over the years have worked flawlessly.

I'm even more surprised because I have let my Tunze ato pump run dry weekly for about 4 years and it still works like a charm.

Kent Float Valve

I use 2, 1 in the sump, 1 on RODI outlet. 5 or more years now, and never once over filled my tank. I have an electric solenoid on my RODI tank for if my sump overfills i use as a backup. The electric shutoff has failed at least twice now when i'm cleaning the tank and it doesn't shut off the solenoid.

In the end, Crappy float valves have been the most reliable.

In my old setup I had a double setup. Basically, the first sensor is for control to start and stop the auto top off. That one is fed through another auto top off which is just a secondary shut off. Both systems have to be satisfied to feed water. If the first one fails, the backup will de-energize the auto topoff pump.

I did this after flooding my tank and the salinity dropped to 1.010!

What I use is a solenoid after my ro/di storage tank on a timer,every 2 hours on for 1 minute and as a back-up I use a big float valve in my sump, if the water rise to much it will stop from overflowing. Having it for 2 years and never had a problem..100% safe. Cost me 50$ all together

I ordered them in bulk (10) from the manufacture over seas. I can try and find out the brand name if you want

With no moving parts they are awesome. I made two different version. One uses a float at the backup sensor and the other uses an optical sensor
http://images.tapatalk-cdn.com/15/07...ae95846d2c.jpg

I like my salinity precise :)


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And I bravely topoff from a 90g tank. Think this is my 5th osmolator and no problems.