Ato

[Chase31]

Was Thinking about making my own ATO for my 35G(all together) tank,my plan was to have a 2L bottle with two airline tubes one long one short, when the short one comes out of the water it will allow air into the bottle and thus releasing water into the tank,

The only problem i see is will the salt diffuse into the water in the bottle instead of having freshwater go back in?

[Binare]

If it does work for ya, I can see you getting annoyed with it within a week tops. My ato on a 15 gallon I have uses more then 2 litres a day, how bigs your tank?

[Chase31]

the display is 30G and the sump is 5

[mike31154]

Not sure I totally understand your concept/design. Will this involve gravity feed or only ambient air pressure to provide the force to move the water? If it's the latter, I'm not sure that ambient pressure would suffice to keep your tank topped up consistently. Ambient air pressure tends to change with the weather.

I use something similar with the long/short rigid air line in a tightly stoppered glass wine carboy, but it uses an air pump on a timer to pressurize it. There's a check valve between the air pump and the carboy and a mechanical humidifier float valve in the display to regulate the level & prevent overfilling. The air check valve downstream of the air pump is to keep the carboy pressurized rather than to prevent water from feeding back since the shorter air line pretty much takes care of that. The mechanical float valve is mounted above the water level in the display, so feedback of saltwater back into the container is also a non issue. A future build will involve a basement sump and I plan to use the same principle, sans air pump/timer. The container will be mounted above the sump and gravity will take care of the flow from the top off container.

Low tech but reliable. It's been working very well since I got the timer schedule dialed in to keep up with the evaporation rate. Even if I run the timer longer than necessary, the small air pump is unlikely to overpressurize the carboy or pop the top off. The mechanical float switch does a great job of regulating the level since it's designed to deal with a home's water pressure which is substantially higher than what will ever come out of the carboy.
Possible failure scenarios include:
Timer/air pump failure = no top up resulting in level dropping;
Leak in any of the lines = same as timer/air pump failure and/or spillage on floor;
Blockage in any of the lines = same as timer/air pump failure;
Mechanical float switch stuck open = overfilling of display;
Mechanical float switch won't open/plugged = same as timer/air pump failure.

Most of these failure modes are unlikely with regular maintenance and observation.
Advantages aside from simplicity:
Minimum of electrics involved;
No electric float valves to worry about;
Top up rate is slow/consistent meaning water chemistry fluctuations are minimal & in event of float valve failure, overfill disaster takes some time to happen

Carboy holds about 7 gal US and is good for 5 to 6 days on my 77.

[lastlight]

Is it not possible to just have a reservoir high up on a shelf and have it gravity feed a float valve?

[mike31154]

Yes, by all means, that's my plan for the basement sump... if I ever get that project off the ground. The simpler the better IMO.

[schroeder]

yes.

That simple solution works. But you may be able to dispense with the float valve as well.

check out nanoreef and see what some folks with pico tanks are doing with pet bottles (meaning hamster water bottles) for simple ATO with no moving or mechanical parts, like this one on a 1.5 gallon tank...

5554b48857ad9681.jpg

I don't know how well this would scale to a larger tank, or larger resevoir, but it's worth a test, with and without a float valve.
Try it out. Let everyone know. Be a hero.

[Chase31]

maybe ill have a gravity fed with a toilet float kinda thing, idk im worried about my salt getting to high :s maybe ill just go buy one for $100

[mike31154]

Not sure I get your issue with the 'salt getting too high'? If you're using RO/DI or fresh water to top off, it should be all good.

[Chase31]

currently i do not have an ATO and i need to get one b4 i put live rock in or ill be toping it off by hand every day