Instan siphon break without check valve

[BlackTip]

Few days ago, I posted a thread seeking help to break a siphon in my redundant dual-return pump.

http://www.reefcentral.com/forums/showthread.php?t=2509871

The obvious choice was to install a check valve, however I didn't want to, because they are unreliable.

I experimented with few designs, until I found a solution. At the return elbow, I drilled and installed an L-shaped John Guest fitting above water line. The result was excellent. The siphon breaks immediately when one pump is shut off. Not only that, but the siphon breaks instantly when both pumps are shut off. No water are back siphoned from the DT to the sump; only from the overflow box.

In the photo, the return line on the right is connected to a pump at 500gph. On start, a little water comes out, then stops. The return line on the left is connected to a pump at 625gph. When the elbow is facing down, some water flow through the fitting to the tank. When it is facing up, a little water drips at starts, then stops. That is why one facing up and the other facing down. Depending on the total flow, a tube may be needed. I didn't need any tubes in my case.

 

[smartandfast]

This concept has been around for a long time. Pretty much the same as drilling a small hole for air right underneath the elbow...

 

[laverda]

Just make sure to clean every few months as evaporation/salt can clog them over time, making them useless.

 

[woodnaquanut]

Just make sure to clean every few months as evaporation/salt can clog them over time, making them useless.

+1

That few drops coming out at startup will create a salt plug in no time!

 

[BlackTip]

+1

That few drops coming out at startup will create a salt plug in no time!

Thanks for the heads up. I will keep my eye on it and see how it function. I still have the anti-siphon holes for backup.

 

[karimwassef]

Doesn't it pull air bubbles in?

 

[BlackTip]

doesn't it pull air bubbles in?

no

 

[karimwassef]

I'm curious why it doesn't. Is it just that the flow is low compared to the pipe diameter?

 

[ghatter]

I'm curious why it doesn't. Is it just that the flow is low compared to the pipe diameter?

That's my guess. I would have never thought to try this since it seems like it would either spray water out or suck air in, but neither seems to happen.

 

[karimwassef]

Anyone smarter than us out there with an answer?

 

[BlackTip]

My guess is the same as yours. The pipe is too wide for the flow. To suck air in, a vacuum is probably needed.

 

[sleepydoc]

It's a pressure thing. There is probably very little net pressure at the opening - positive or negative - when the pump is running. It's a large pipe with the opening immediately below the surface. When it starts to siphon, there is a relatively large net negative pressure, causing it to suck air in.

 

[karimwassef]

I'm trying to solve the same problem but I have 5 pipes at 2" diameter running 1000gph each... How can I tell if this will work?

 

[sleepydoc]

Try it?

 

[karimwassef]

I'm designing a new system. I can either put in separate inlet chambers now or try this without the chambers. If I go without chambers, trusting this will work, and then have it not work: I'd have to break down the tank and redo it.

The only reason I'm thinking about this is the complexity of constructing five inlet chambers compared to drilling five little holes and adding tubes...

 

[sleepydoc]

can you just mock up one with some fittings and a plastic pail to see if it will work?

My big concern with this system is taht it would get occluded with salt creep. you could keep it clean by cleaning out the holes every few months or so,, but that kind of maintenance tends to get forgotten over time...

 

[woodnaquanut]

can you just mock up one with some fittings and a plastic pail to see if it will work?

My big concern with this system is taht it would get occluded with salt creep. you could keep it clean by cleaning out the holes every few months or so,, but that kind of maintenance tends to get forgotten over time...

+1. I'm a big fan of not having to maintain it just so it works. Putting the returns in so they naturally break siphon is much better than all the alternatives.

 

[karimwassef]

Would intentionally turning the pumps off for a minute every day provide a natural wetting and cleaning event? "Self-healing"

 

[BlackTip]

Everything single piece of equipment requires maintenance and cleaning. I don't see keeping those fitting clean is any more more work than other options.

Turning the pumps off at least once a day for feeding will activate the fittings, and one should notice if they are plugged. Also, getting in the habit of sticking a q tip in the them every 2 weeks during water change is not that all difficult.

 

[davocean]

+1. I'm a big fan of not having to maintain it just so it works. Putting the returns in so they naturally break siphon is much better than all the alternatives.

Agree, siphon breaks are an ok plan B when you have a tank that does not have return lines high enough for an early break, but it's still not the optimal setup.