DIY ATO using Pressure

[Nick Rose]

I’ve been doing fresh top off water by dripping it into the tank once a day. I aim for 35ppt and it never goes above 35.6ppt using the drip method. I was wanting to update it with using pressure. This is what I’m talking about. Ive tried it but it’s not working. Everything is air tight. Don’t know if I’m missing something.

DIY: Tea Jar Auto Top-off | Reef Builders | The Reef and Saltwater Aquarium Blog

If you need a great DIY auto top off device, then you might want to look at this clever invention. The auto top off uses a Sun Tea jar, and a air tube that fills the tank automatically.

reefbuilders.com

 

[Brett S]

It’s an interesting idea in theory, but I don’t think that it can work in practice. Air and water compress at different rates, so as the tank fills with air the air will be able to expand more than the water that it replaced can and you will be ‘dosing’ more water when the tank has a lower water level than when the tank is full of water.

I am using a gravity fed system for my ATO. I have a reservoir mounted higher than my sump (it’s actually in my garage) and I have a line fed from there to my sump connected to a float valve. I also have an added safety of a solenoid and a float switch controlled by my apex.

 

[P-Dub]

Two things.
What part is not working out? i.e. not flowing or flowing too much...
AND

 

[P-Dub]

It’s an interesting idea in theory, but I don’t think that it can work in practice. Air and water compress at different rates, so as the tank fills with air the air will be able to expand more than the water that it replaced can and you will be ‘dosing’ more water when the tank has a lower water level than when the tank is full of water.

I am using a gravity fed system for my ATO. I have a reservoir mounted higher than my sump (it’s actually in my garage) and I have a line fed from there to my sump connected to a float valve. I also have an added safety of a solenoid and a float switch controlled by my apex.

It will and does work, it's physics in action. You just need things properly sealed and lines that are appropriately sized.

 

[Nick Rose]

Two things.
What part is not working out? i.e. not flowing or flowing too much...
AND

I was putting in a new circuit for the reef tank but I had to put it on hold. So those wires aren’t hooked up to the new circuit.

 

[Biokabe]

I've tried it before. It worked intermittently, but on the whole I found it just was too finicky. Once the water reservoir got below a certain level it just stopped working. As the pressure within the container increases, the water can absorb more air, and eventually you get a situation where it's easier for the pressure to relieve itself by air backflowing through the airline than it is for the water to flow out of the dripline.

With a more powerful air pump and better seals, it probably would have worked better, but there's a reason that none of the commercial ATO solutions use pressure instead of water pumps.

 

[Brett S]

It will and does work, it's physics in action. You just need things properly sealed and lines that are appropriately sized.

I think it will work, in that it will dose some water each time air is allowed to enter the tube, but I don’t believe that it will dose the same amount of water each time when the reservoir is 90% full, compared to 10% full. I guess how much of a difference it will be depends on the size of the reservoir, and frankly small differences will probably be pretty negligible compared to the amount of saltwater in the system.

 

[count krunk]

I wouldn't even bother with this. There are much easier ways to get your ATO to work

 

[P-Dub]

I was putting in a new circuit for the reef tank but I had to put it on hold. So those wires aren’t hooked up to the new circuit.

Still waiting on the answer to part one of my post...

 

[Nick Rose]

Still waiting on the answer to part one of my post...

It flows when the air intake is below the water line in the sump. So when it should stop flowing it doesn’t.

 

[P-Dub]

Most likely it is not, in fact, sealed then. Those "pasta" containers are not always airtight. Try using electrical tape on the seam and silicone grease at all the connections and test again. Additionally, you may need to change the tubing size.