pvc overflow - losing siphon

[coolkeith]

IME, aqualifters eventually do NOT work on more than one overflow. In my case, the aqualifter sucked water from the highest overflow and the water siphoned down to the lower overflow.

 

[oregonian]

you should try adding some pipe inside the tank so it pulls from farther down. just in case somehow its getting air bubbles from the surface some how. i know its not likely but worth a test. don't worry about if it goes lower than your outside pipe as it doesn't matter on this type of OF.

another note but doubt it would be causing the failure but alot of check valves can be ruined if water gets pulled through them, causing them to not seal properly.

 

[MyFishEatYourFish]

sounds to me like the intake is getting bubbles that are too big for it to suck through. i just got done doing an overflow and had the same problem. that also explains the inconsistant failures. you can move the check valve to the back elbow where the bubble collects or run the overflow to its maximum potential so that is sucks even large bubbles all the way through.
i would suggest trying to use smaller pipe for the "u" part to speed up the water flow and lowering the large portion to get the extra head. i don't know if you have the extra sump room for water though, but its an option.

 

[KaiserSousay]

smaller pipe for the "u"

+1
Or larger pipe for "collector"..a clear U tube would answer alot of your questions, as well..not as cheap as pvc, but not all that pricey.

 

[mjohns]

I think i can solve your problem, my overflow is not the same but still works the same.

I used no checkvalve just airline and hooked the other end up to my 1200lph pump with sponge filter, you know where youd normally hook the airline to pump bubbles into your water jet..

Its hard to explain but instead of sucking air through it sucks some water mixed with air occationally i see it spurt some air out..

This is the only way i got my overflow to work properly, it even has enough suction to clear my whole pvc overflow of air and starts up flawlessly (i did find if i had my pump lower in the water it didnt have as much suck)

I really hope this makes sense, as im 100% sure it would work.

Goodluck.

By the way i have seen no solutions suggested other than getting a aqualifter, and if you do what i suggested its basically the same thing.

 

[Danger_Chicken]

Thanks for the ideas. A smaller u pipe wont do much for the speed since this is being use to drain a drip system (straight to the drain); so, there will only be .5-2gph going through it depending on which tank. Anyone know where I can get some clear tubing?

I'm trying to picture what moving the check valve to the back elbow would do. As far as I know the check valve is only used to manually suck the air out to start the siphon, not an ongoing air release. I could be wrong.

 

[mjohns]

Ok take no notice i dont care, why suck on it every day and risk losing syphon and be constantly paro when u can just hook it up to your pump which sucks any air out of your loop as soon as it sucks it in from your intake.. DUH

Eh maybe you will figure it out some day..

 

[Danger_Chicken]

I didn't see you post until now as we were posting at the same time. Do you have any pictures?

 

[mjohns]

I just took these for you.

Its really quite simple, but hard to explain.

 

[mjohns]

Also I would put the airline where the checkvalve is now, minus the checkvalve.