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Syphon problem


ant265
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Hi all,

I have an undersize sump (rather return is too low), how can i stop water syphoning the tank through the return line of pump and flooding sump? I have thought about a one-way valve i got told about, also heard of putting hole in pipe just under waterline (undesirable). When was trial run the bulkhead was leaking between nut and thread it appeared, does it need to be tightened by a tool as I have never needed to tighten one more than hand tight on other tanks (they dripped a little but sealed once calcified). Tank is currently empty for repairs to background.

Any help/advice greatly appreciated

Cheers

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Option 1 a one-way valve,

Option 2 put a hole in pipe just under waterline (works for me).

Option 3 use a spray bar above the waterline

Bulkhead problems....

Are the seals around the right way? Mine has lots of silicone for security.

My durso seals well into bulkhead but easily removable to drain weir.

Make sure that the sump can handle weir & backflow volume when working out maximum sump working volume.

hth,

Old Dave

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Would make sure your sump volume is large enough AND drill an anti-siphon hole. This is not "undesireable" it is essential and common sense. Would not trust a check valve but you can put one in if you wanted to. If you do, use a rubber hinged one, not a spring loaded one although neither are 100% foolproof

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Good advice so far guys.

What i am mainly concerned about in regards to the hole in return is when the pump is pushing water through i dont want to see water squirting out the hole to look like a leaky hose. What size diameter would be needed to let in enough air to break syphon? I guess just start small and slowly make it bigger til suitable size is reached

Cheers

Ant

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:thumb Put a 90deg bend on your return to lift it higher if your return is to low, you can use a reducer to make the return pipe smaller, but is your pump to big for the tank?

Drill hole in bottom of hose close to pump. Hole size depends on amount your stopping going to tank. Try 2mm first then increase if needed.You dont say sump size Tank size or pump or hose so we are guessing. Up top you say you need less water going to sump but if you reduce outlet your tank may overflow form amount of pumped water.?.

Edited by dobbin4
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Bulk head fittings - put silicon between rubber and glass, just a thin worm once around right next to the threaded inner side of gasket doenut. Tighten by hand then with a tool nip it just a touch. Make sure O-ring surface of gasket and bulkhead has not got a scratch no matter how small, and that there is no matter on the glass surfaces.

You haven't explained your plumbing issue well enough as you say the "return is too slow", but I gather you have a back syphoning issue when power is off and sump is too small to hold all return water? The outlet can only out-flow a volume of water = to the amount the pump, pumps, so if the return is too slow, you need a bigger pump (with tubing to match)

However, if the pump size is not your issue, dobbin4's comment regarding making the lowest plumbing point higher will prevent back flow the best.

One way valves can be problematic, spinged ones need great pressure to open (which you haven't got) and regardless of type they will A) slow down water flow and B) if anything gets caught when power is off, the one way in effect will be open, and one way to the floor.

You best bet is probably to raise the lowest point in your plumbing where the water is back flowing out, but a lot more clear details are required to make a more definite comment.

Edited by CThompson
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Would make sure your sump volume is large enough AND drill an anti-siphon hole. This is not "undesireable" it is essential and common sense

Fishdance,

Undesirable in sense i didnt really want that is what i was getting at as i want a clean look but seems inevitable now so its all good and i dont want to buy/make another sump if i can help it.

You haven't explained your plumbing issue well enough as you say the "return is too slow", but I gather you have a back syphoning issue when power is off and sump is too small to hold all return water?

Craig,

Return is too 'low' and therefor yes sump is too small because of the U-bend that hangs in the tank from a large canister filter. This is where the hole needs to be by the sounds of things.

Put a 90deg bend on your return to lift it higher if your return is to low, you can use a reducer to make the return pipe smaller, but is your pump to big for the tank?

Drill hole in bottom of hose close to pump. Hole size depends on amount your stopping going to tank. Try 2mm first then increase if needed.You dont say sump size Tank size or pump or hose so we are guessing. Up top you say you need less water going to sump but if you reduce outlet your tank may overflow form amount of pumped water.?

Dobbin4,

What do you mean by 90deg bend to lift it, how would it? The tank is a 5x2x2 with a 2ftx50x50cm sump with an OR6500 pump and flows just fine (might not drain quick enough if my memory works correctly) so by putting a hole close to pump is not what im after just yet rather if pump goes off the water coming back through pump hose will overfill sump.

Thanks for help so far guys

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When was trial run the bulkhead was leaking between nut and thread it appeared,

Did you use plumber's tape on the thread before putting it together?

Not needed Skippy, the gaskets should do the job. A plumber friend on these pages told me and he proved it correct, plumber tape is not needed when there is a gasket or an O-ring seal and may make it worse. I had a leak I couldn't stop with tape, he removed and reattached and it stopped.

I always use a bit of silicon but that's because that was how LifeGuard recommended the installation of their airline bulkhead fitting, and I have always figured ever since that it can't hurt.

Sorry Ant, I don't understand what your issue is, I feel that there is something going on here that does not need the hole, or that is better fixed another way.

If is that your sump is too small to hold the backflow (as I think you are saying), what you are trying to do is limit the amount of water that flows back to the sump?

1)If that is correct, the best way is to raise the lowest point in the tank that flows back to the sump. I did this once by using and elbow immediately on the inside of the tank (hole was drilled in the end wall near the back wall of tank). So, bulkhead fitting, elbow, straight piece then end cap. I drilled the straight piece with airline hose sized holes and fitted plastic airline elbows and organised it so these holes faced straight up with the elbows directed forward (down the tanks). This effectively raised the lowest point of exit from the return to the tank by a few centimetres.

From the outlet size of the tank, if you have your bulkhead fitting, attach to this on the inside of the tank an elbow which can swivel to face more upwards, creating a higher point of exit. You can add a strainer to the end of this elbow.

If you go with the hole method, dependant on how long is the drop to the sump, there can be a lot of suction, and the water just keeps draining.

In essence what you have to do is stop so much water from going back to the sump, and 1 & 2 above, if I’ve understood your issue, are the best solution, next to getting a bigger sump.

Edited by CThompson
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Sorry Ant, I don't understand what your issue is, I feel that there is something going on here that does not need the hole, or that is better fixed another way.

If is that your sump is too small to hold the backflow (as I think you are saying), what you are trying to do is limit the amount of water that flows back to the sump?

If that is correct, the best way is to raise the lowest point in the tank that flows back to the sump. I did this once by using and elbow immediately on the inside of the tank (hole was drilled in the end wall near the back wall of tank). So, bulkhead fitting, elbow, straight piece then end cap. I drilled the straight piece with airline hose sized holes and fitted plastic airline elbows and organised it so these holes faced straight up with the elbows directed forward (down the tanks). This effectively raised the lowest point of exit from the return to the tank by a few centimetres.

Exactly right Craig but I dont completely understand what your suggesting or sure that i can do it with what I've got set up (lowest point would be where water comes out of pump return in tank you mean?). I don't think i particularly want to use pvc even if i could.

Think i need to try put pics up to better understand my needs and peoples theories/ suggestions. Thanks for help and appreciate patience on this

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