Check Valves

[TBout86]

Going back and forth between hard or soft plumbing for my return.
I have 2 returns, both opposite sides of a the aquarium. So I will be splitting my main return line from the pump.
Is there a check valve for soft plumbing?

many one have some photos of their own they can post photos of?

 

[Dégatdeau]

I woukd suggest you dont rely on check valves to keep your tank from draining when you turn your pump off. They have been known to fail. Instead, keep some room ij your sump and drill a small hole in your return just below the surface so that it breaks the syphon

 

[Midwater]

I use a check valve mounted vertically on the return pump. I agree with other posters that say that check valves are not necessary - in general.

If there is a power failure, the water in the top of the overflow will siphon back through the pump into the sump, which should be able take that extra volume in the settlement chamber. Fair enough if there is a power failure that lasts longer than it takes the water to siphon.

There can be a problem if the power is restored while the water is still siphoning. The back pressure of the siphon can be equal to or even more than the return head of the pump. This can cause the pump to stall and the impellers to stick. It should all start again so, but if it does not, then you burn out a good pump.

So you have to way this up against the slight loss of head due the check valve, and the possibility of it failing.

I have used ball check valves for decades on swimming pools, and have never had one fail.

On my large tank, to, I use a check valve on top of the Iwaki return. Iwaki recommended it.

At first I used a spring check valve. I never liked it and did not think much of the quality. I was worried about spring, which as I see it is the only thing possible to fail. It was also noisy.

Ball check valves are easily available at 1 /12 inch and 2 inch for swimming pools, but I found it difficult to find a one inch ball check valve. I did get one, it was significantly more expensive that the spring check valve. It seems to work well, reduces head minimally.

But it is noisy too. The ball rattles in the housing with the flow. I do not much like this. I use a Herbie from the overflow and the pump is reasonably quiet. But I am aware of the bloody check valve. I even wrapped a cloth around it to dampen the sound.

As for your question about soft plumbing. The valve should be mounted vertically directly over the pump. From the outflow of the check valve, I do use soft plumbing - non collapsible spring hose - and use a fitting with a thread on one end into the check valve, and a pagoda on the other end into the spring hose.

 

[fishdance]

The idea is to prevent any back siphon occuring but the force of water siphon is not going to stop your magnetic pump impeller.
Even at 2m drop, the pressure is a ridiculously low 2.85 PSI.
Assuming your pump is relatively small with a low water head capability, it would simply resume once any blockage clears.

That said, if having a check valve provides you comfort then use it. For some people, not having a check valve provides comfort.

 

[brent245]

I'm setting up a 350g tank in a couple weeks. It will have 2x 1-1/4" returns. I plan to do hard return pipes up over the rim of the tank. I saw another person do this and they glued a 1/4" barb fitting into a hole they drilled in the pvc at the top right as it goes over the rim of the tank. A 1/4" vinyl tube was installed on the barb fitting and then they clipped the tube to the rim of the tank and aimed into the tank. So even if the return pipe is underwater the tube is still out of the tank and will break siphon if the pump stops.

 

[fishdance]

I don't remember if I've previously posted but in situations where a check valve must be used, a reverse check valve is less prone to failure.

Use a horizontal stub pipe at the highest point that terminates with a check valve placed backwards ..... so pump when running forces the check valve closed. It's only when the pump stops that the check valve opens which breaks any backsiphon. On large diameter pipes (80mm - 150mm) a break siphon hole may take too long to work. Even large air pockets continue to get dragged through for several minutes. Use appropriate sized check valve.