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Cheap, reliable ATO?

svreef

Supporting Member
It just occurred to me that I already have an ATO system in my house that has been running without a flaw for years...the ice maker in the fridge.

I’m willing to bet that using commodity ice maker parts (and an optical sensor), one could fashion a cheap, reliable ATO that is directly connected to the RODI supply.


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Coral reefer

BOD
Staff member
You really do not want it directly connected to water supply in case of failure.
Your new sump has a built in ato Rez by the way...
Auto aqua smart micro is about $130 and works well

Auto top off dot com is like $60 and very reliable
 

svreef

Supporting Member
Yeah, I know...I’m trying to challenge the thinking that you don’t want it connected directly to the supply because it’s not reliable. I’ve never heard of a fridge flooding the house due to an ice maker failure.

So, why are the existing solutions unreliable?
Why are ice makers presumably reliable?


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Flagg37

Supporting Member
Yeah, I know...I’m trying to challenge the thinking that you don’t want it connected directly to the supply because it’s not reliable. I’ve never heard of a fridge flooding the house due to an ice maker failure.

So, why are the existing solutions unreliable?
Why are ice makers presumably reliable?


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I agree with you that there are elements of our hobby that go way overboard with redundancy and fail safes. Sometimes it’s a good idea and other times it just seems ridiculous. In regards to this situation I don’t see it as necessarily a possible point of failure but you need to think about the DI depletion rate. If you hook up your RODI directly to the tank then it opens and closes the valve numerous times a day. The water that sits in the RO membrane increases in TDS (referred to as TDS creep) and when it opens the next time it flows to the DI and exhausts it much quicker. Sometimes it can be well over 100 TDS instead of the 5 or so that the RO typically puts out.

I didn’t usually flush my RO membrane to get rid of the extra TDS because I would turn it on and let it run over night to make about 55 gallons at a time. That extra TDS at the beginning seemed negligible to me.
 

bondolo

Guest
I used a plain eShopps float valve directly connected to my RODI tank successfully for 7 years. I liked it because it was unlikely to "fail on" and cause flooding or over-top-off. On one occasion the float nozzle got clogged with a tiny bit of grit but it was otherwise flawless. The RODI storage tank also had a float valve but I usually tried to manually cycle the RO supply as it is not recommended to run RODI systems in drip mode.
 

rygh

Webmaster
Staff member
Apex, pump, and a couple of float switches. Cheap, reliable, and you can log it.

But like others, I do not connect pressurized RO directly to the tank.
Although in all the years of filling my RO barrel, that float valve has never failed.
 

JVU

BOD
Staff member
One big difference is that compared to an ice maker, a sensor or float valve in your tank is exposed to a lot more variables that could fail a sensor like critters, precipitate, algae, debris, etc.

Another difference is that fresh water on the floor in the kitchen is a lot less of a disaster than dropping the salinity of your tank killing livestock, and salt water on the floor is also much worse than fresh water.

The TDS creep of frequently briefly running RO/DI output is a real factor, and will make you go through DI resin much faster.

What I do that works great but isn’t cheap or easy: RODI directly fills via a water controller a 5 g bucket when the water level gets down to the last gallon. Then my ATO runs from that bucket to my tank. The RODI-fed bucket is in the garage where a spill wouldn’t be a disaster, and the sensor in the bucket isn’t exposed to tank variables.
 

Wlachnit

BOD
Staff member
FWIW, I've been using an inexpensive mechanical float valve (connected to a 15g RODI reservoir) for 14y on my 300g DT. I've replaced it only once about 7y ago. I have thought about replacing it with something more sophisticated, but what I use works...so I never have.
 
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