Back Syphoning

[fatfishman]

Hello there everyone one i just have a quick question for you about the return from my sump to my display tank.

My return pipe enters the main display tank through the base in each corner then a rigid spray bar fits on top of them which runs the length of the tank. I was wondering what precautions can be taken to prevent back syphoning (and 650 liters of saltwater into my smallish sump, which i must avoid at all costs) in the event of the pump breaking down or a powercut, i want to take every precaution possible. Bearing in mind that the piping enters the tank through the base.

Thankyou for reading and all of your previous advice guys

 

[SkiFletch]

Anyway you can take a pic or do a mock diagram? I'm not exactly sure from your description how its setup. You should always have 2 levels of protection. First off would be a true union check valve, and second should be a means of breaking siphon. In my tank I just have the returns up high enough so that if the check valve does fail, they'll see air and break siphon

 

[ozzy47]

i got around back syphoning by, just above the water level in your sump on the return pipe, drill a small hols the diameter of a piece of air tubing, insert the air tube, when the sump pump fails, powercut etc, the air tube takes in air and stops the back syphon, but make sure the hole/airtube is over your sump becuase obviously when the pump is running water comes out of the air tube, to me this is better than having 650 litres of water back fill in a sump and all over your floor.

cheers stewy

 

[fatfishman]

Thanks ozzy47, but i thought if the hole with airline in it is below the display tank level thatn it will continue to syphon out of it any way or am i wrong?

And Skifletch i have knocked up a quick diagram for you take a look and see if you can make sense of it, sorry for the poor explanation in the original post

You will need to enlarge it.

As you can see the return pipes enter up through the base,

Cheers guys

 

[ozzy47]

hi mine works fine as long as it is not under water/in water then as soon as the pump stops then the air line will take air in and stop the backfill, failing that for £2.95 on ebay get a non return valve.

cheers stewy

 

[andywg]

That is a less than ideal design. While in theory you can install in-line non return valves to close the return pipes when the pump turns off, there is always a chance they will fail, and most are not even rated 100% (meaning a small amount can and will leak over time if the power is off).

You are much better having the return pipes above the water level and going down into the tank with a pair of holes drilled at about the water line to prevent it being able to back syphon.

 

[fatfishman]

Ok thankyou ozzy47, does your return pipe enter through the base like mine?

Andywg I know this is not great but my tank is already drilled and such so there is not alot that i can do.

If anyone else has any ideas please make them heard as im quite worried about it now

 

[andywg]

Ok thankyou ozzy47, does your return pipe enter through the base like mine?

Andywg I know this is not great but my tank is already drilled and such so there is not alot that i can do.

If anyone else has any ideas please make them heard as im quite worried about it now

Less than ideal, but you can extend the pipes straight up so they break the surface and then loop back down into the bottom and the spray bar. Where the pipes break the surface you drill the anti-syphon holes (at least two on each as sod's law tells you that there will be a snail on one when you have a power cut )

 

[fatfishman]

I understand what you mean Andywg so something Like This:

Ozzy47 is your sump tank above your display?

If anyone else has an idea please let me know

Thanks Again

 

[andywg]

I understand what you mean Andywg so something Like This:

That's exactly it, though remember to make sure that the pipe extends above the water line. Then work on buring the pipes with Live Rock to hide them from view

 

[fatfishman]

I understand what you mean Andywg so something Like This:

That's exactly it, though remember to make sure that the pipe extends above the water line. Then work on buring the pipes with Live Rock to hide them from view

Ok thanks Andy i will be sure to set it up like this when i move, unless there are other possibilities, its a little more piping but IMO opinion its much better to be safe then sorry

Thanks alot

Ozzy47 i tested the method you mentioned and the syphon only stops once the water level reaches the height of the airhole, and as my sump will be lower than my tank this will not work for me, I dont think so anyway unless Im missing something.

If anyone else has any suggestions please do not hesitate to tell me