anti-siphone device

[lonhater]

I'm struggling to figure out how to construct an anti-siphon device for my ATO line. My rough design is below. The issue involves the 1/2" ID (5/8" OD) silicone tubing that runs from my freshwater tank to my sump for ATO.


Right now, when the ATO sensor is triggered, the pump turns on and fills the sump. Once the controller shuts off the pump, I notice water continues to slowly trickle into the sump. With 30 feet of water sitting in the line, I’m not sure if this is just residual water draining or an actual siphon but I suspect it’s a siphon. Thankfully, I haven’t found out the hard way...


From what I’ve read, I need to introduce air into the line using some kind of anti-siphon device. That means I’ll need to install a tee in the line around the question mark in my diagram. But I’m stuck on how to connect that tee to an anti-siphon device. And since I’ll also need to do this for my saltwater line, I need something marine-rated and reliable and can't get close to a good product.

Backflow shouldn't be a problem but I did install a check valve just to be safe. The hose outlet will be above water at all times unless this anti-siphon device has already failed or the pump fails on? Another problem for another day

This seems like it should be a simple, common solution, but despite a lot of searching, I’m coming up empty. Has anyone here dealt with this before?

 

[commod0re]

Anti-siphon can be as simple as a small hole in the line a bit above the max water level, but still inside the reservoir.

I just set up the red sea ATO+ a couple hours ago and the anti-siphon device it comes with is essentially just a leaky coupling

 

[lonhater]

Anti-siphon can be as simple as a small hole in the line a bit above the max water level, but still inside the reservoir.

I just set up the red sea ATO+ a couple hours ago and the anti-siphon device it comes with is essentially just a leaky coupling

Huh like drilling a 1/8" hole in the hose above water line? Would that not screw with the pump?

 

[commod0re]

Yeah basically. The idea is that once the pump stops, water falling back down the tube draws air in, breaking the siphon

If the hole is small enough, like with a leaky coupling or something, then the loss in pressure will not be too great for the pump to overcome and get water up to the tank anyway, and if it leaks back into the reservoir then you didn’t lose any of it or make a mess either

 

[fish_collector]

It's a lot more expense, but a peristaltic pump won't allow a siphon. It would go near the sump and not in the ato tank. It could still be turned on and off with the ato controller, which I assume would just be a 12v signal. A Spectrapure Litermeter pump module is just a peristaltic pump that runs from an external 12v source, and would last many years before it gave you any trouble.

 

[lonhater]

Yeah basically. The idea is that once the pump stops, water falling back down the tube draws air in, breaking the siphon

If the hole is small enough, like with a leaky coupling or something, then the loss in pressure will not be too great for the pump to overcome and get water up to the tank anyway, and if it leaks back into the reservoir then you didn’t lose any of it or make a mess either

I did it, I drilled a 1/8" hole in the hose inside the reservoir. The water shoots out of it like crazy when the pump is on but stays inside the tank. It breaks the siphon, thanks! I still worry about the salt line clogging over time. But this def buys me time to figure out a back up plan. Thinking about buying a traditonal sprinkler vaccum breaker and building a manifold for the RO, Salt, and water lines to go through as a fail safe. Thanks again for the idea and I removed my jimmy rigged ATO now and switched to my mixing station for ATO. AWC next :)

 

[lonhater]

It's a lot more expense, but a peristaltic pump won't allow a siphon. It would go near the sump and not in the ato tank. It could still be turned on and off with the ato controller, which I assume would just be a 12v signal. A Spectrapure Litermeter pump module is just a peristaltic pump that runs from an external 12v source, and would last many years before it gave you any trouble.

peristaltic pumps seem better in a lot of ways. I'm excited about the kaomers on my x10 for dosing. But 300 mL/minute-ish is just too slow for me for AWC. I want to turn off my return, drain the sump and refill in 5-10 minutes. To do that with a peristaltic pump would be expensive like you said :( But you got me thinking that because the freshwater line is going to be used numerous times a day and speed doesn't matter as much so it might be worth getting one for ATO.

My wife really doesn't want wet floors

 

[fish_collector]

Yeah I was thinking of a peri pump for your ATO to eliminate a siphon condition.

 

[waqas_01]

Can you put a tall pipe in your sump? Basically have the rodi water supplied to the sump at a level taller than your rodi storage tank.

Second option is to hook up a small ato container with a float valve to your larger storage tank. This will keep the small container full all the time. Then put your pump into the smaller container and again pump it into your sump at a higher level than your small rodi container. The siphon will drain the water back towards your container rather than the tank.

I use the second approach for the last 5 years. Works great.

 

[KStatefan]

 

[lonhater]

Yeah something like this would be great. I never added bulkhead to my search terms dang. Thanks

 

[waqas_01]

Is the siphon causing too much rodi water to be put into your tank or are you draining tank water back to the rodi reservoir?

I think the bulkhead fitting above will only work to prevent tank water from draining back to your rodi reservoir. Unless if that fitting has something new that I don't know about.

 

[lonhater]

Is the siphon causing too much rodi water to be put into your tank or are you draining tank water back to the rodi reservoir?

I think the bulkhead fitting above will only work to prevent tank water from draining back to your rodi reservoir. Unless if that fitting has something new that I don't know about.

Water is draining from rodi tank into sump after the pump turns of. You seem to be right about the bulkhead being just a backflow preventer. Backflow won't be an issue for me unless my basement is already flooded in which case I'm not worried about it at that point. I drilled a hole in the RO line inside the rodi tank. Works well but not the elegant solution i am still looking for. My RO outlet is in my overflow and the RO tank is 30 feet away in furnace room. Everything is still a mess as I iron out details before I permanently properly land everything

 

[KStatefan]

It is an Anti siphon bulkhead.

 

[commod0re]

all anti-siphon devices are ultimately just a small hole anyway. A check valve to only allow air in could be included as well but it’s the hole that makes it work. 1/8th inch is still kinda large, the hole in the anti-siphon bulkhead that was linked earlier in the thread is a little smaller than 1/64th inch

the only force involved in a siphon is gravity so one way to prevent the forward siphon from happening is to make water climb a hill of some kind. In my case my ATO fills into an aio tank which is directly above the reservoir, so the outlet is completely above the ATO reservoir’s water level, so it’s not possible to siphon from the ATO into the tank

For your case the root of the issue is probably that the outflow into the sump is below the water line in the ATO, because the difference in water level from source to destination is what determines how much force a siphon has. If you can move the outflow point so that it’s completely above the max water line for your ATO reservoir it should solve the problem by removing all of the possible siphoning force for that direction