pvc overflow - losing siphon

[Danger_Chicken]

I built some low volume overflows for a drip system using the design at the link below. They work great but are losing their siphon. I have a check valve on top to suck out the air and I leave the tube on the check value (not pictured) full of water to ensure air is not leaking in past the valve. I also put silicon on the valve were is attaches to the overflow. The pvc is cemented. The 1/2" u-tube inside the 1" main tube is as long as the piece on the outside and a good 2-3" below the T.

Any ideas why it's losing the siphon?

http://www.monsterfishkeepers.com/forums/showpost.php?p=1248187&postcount=5

 

[rallysman]

If that's the duck bill style check valve it's probably bleeding back through. I never had any luck with them. It also might be a good idea to look into an aqualifter. It's just cheap insurance.

 

[Danger_Chicken]

I think it is the duckbill type, but on the tank I have a piece of tubing connected to it that has water in it. That makes me think it's not the valve bleeding back.

Can I use a T to use the aqualifter on more than one tank? I'm trying to do this on 13 tanks and don't want to have to buy 13 pumps if I can get away with 3 or 4.

 

[rallysman]

If they were on a central sump you could, but it wouldn't work well otherwise.

How far down does the tube go inside the larger tube? Is there any air that could be getting into the intake of it? (sponge filter, air stone, etc,)

 

[Danger_Chicken]

The larger tube is about 10" the smaller u-tube is 5-6" inside the larger tube. I thought about sponges filters at first and moved them to the other side of the tank but still had the problem. The intakes are several inches under water.

I've built 11 of the overflows but have only hooked up and put the check valve on 3 so far. I might put a u-tube in without a check valve and see if it holds. That would let me know if the valve is the problem. It just seems to me the valve is the weak link.

I'm not dripping water yet just filling the tank with a bucket to test. Aqualifters would be the best route for sure but that will get pricey.

Thanks for the feedback.

 

[oregonian]

how long does it take before you lose the siphon?

also it may also be where the check valve enters the tube. especially if you put the silicone around it after it was in. best way is to put some on the valve and then insert it. when overflows are running you'd be surprised how much suction they produce and can suck air through TINY holes/seams.

when i checked mine before check valve i ran an airline up the intake to the top and sucked out the air that way. that way i was sure there was no way air was entering from the piping unless from the connection. (make sure after sucking the air out you crimp the line while still sucking or it will pull air back quick)

good luck and keep with it. i am so glad to see more of this type of overflow being used.

 

[oregonian]

oh yeah, i meant to ask about the possibility of debris settling out in the bottom. may not be an issue now but i would kinda worry about not being able to see or easily access it.

 

[Danger_Chicken]

It seems to lose it over night. In one case it did in about 20 min. I super glued the check valve in place and then put the silicon around it. When I put water in the tank last night is still had some suction left after 2 days, so it seems to be inconsistant. I zip tied some foam block from an aquaclear filter to the intake pipe to keep debris out, hopefully that will do the trick.

I love your warning lable, I need one of those.
WARNING: This post may contain sarcasm, friendly taunting and failed attempts at humor.

 

[oregonian]

yeah thanks, ya never know when you may need a disclaimer.

that sucks that its inconsistant, doesn't really help you narrow down the cause. you might want to try a air pressure test. like when you test a bike tube for leaks. seal up the ends and then reverse or remove the check valve and pump or blow pressure in while submerged and watch to see if air bubbles form anywhere.

can we get picks of it in the tank, give us an idea of how the water level sits, how the return lines up and approx where the inside tube sits relative to that?

i like these better than how i built b/c of space so kinda using you as a guinea pig another ? is does the level yoyo, and does it make much noise?

i know alot of ?'s for only a little help but thats the joy of trying a design first

 

[Danger_Chicken]

I have my basement setup into sort of 3 differnt fish rooms. The laundry room has growout and feeder breeders. That's where this project rest now. I have one drain line running along the wall that 4 tanks connect to and drain into the utility tube. All of the pic's are of a snail and shrimp tank. The water line is about 2" low so the snails can lay their eggs out of water. That's one nice thing about these overflows is you can adjust them to put the water line where you want it. The system is quite, there is a short video, 95% of the noise is from a 5g in the sink with a bubbler on it. The rest of the noise is from the drain into the sink. You wouldn't hear the drain if it wasn't right next to the tank. The tanks in the other rooms will have the drain run to the basement sump in a closet so it should be silent.

Full setup - I kept that long air line full of water to stop back seep.

Close-up connected to tank

Drain line

Intake with filter foam

Poor quaility video - before the upload to youtube you could see the water draining.
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