Why isnt my overflow working properly??

[vinxs]

Hi all,

After a countless number of tutorials ive watched, i managed to put together an overflow, but after priming, it doesn't manage to flow, could someone please tell me the flaw in my design? any help would be greatly appreciated

Ps. i have a check valve in its recommended place.

 

[TONY_C]

I've never seen one that looks like that. Can you tell us where you got that from? link? The one I have seen that is similar to that does not have the open end at the top near the water line, it is down at the bottom inside a large tube that acts like a weir.

 

[Jreed983]

I could be wrong here but from looking at the pictures it seems as though the tall stand pipe would be acting as a siphon break so it's letting air in thru that pipe rather than forcing water to be pulled in thru the overflow pipe. Have you tried running it with the stand pipe capped off to see if that fixes the problem?

 

[username in use]

yea, there is no way for the water to go higher than the level of the tank. Why is that tall pipe even there?

I see two solutions. Scrap this and do something more traditional, maybe a premade overflow box.

Or, Cap that really tall pipe completely, then add an aqualifter pump to the airline coming out of the PVC. That should help pull the water up to the top of the aquarium and start the siphon.

 

[Reefingmark]

https://www.youtube.com/watch?v=65yVr7DiDls

Here is the link. I have never seen a system like this but obviously it works! WOW!

 

[username in use]

He does say the outside pipes need to be the same length as the inside pipes. Im not sure what the importance of that is.

Was your ball valve open or closed when you were trying to run it? I know it's a silly question but I had to ask.

 

[bmitchell138]

What about your ball valve on the overflow pipe? It looks completely closed to me.

 

[RocketEngineer]

It's built wrong.

This is what it should look like.

Where you have two tees on the outside of the tank should in fact be two elbows. The result is that the outside pipes look like the inside pipes at the bottom. The drain comes out the side of the vertical pipe creating a small pool of water.

Here is a decent picture showing the idea. See how the water at the bottom of the U inside the tank and the one outside the tank trap the water in the siphon? You're missing it on the outside so when the flow stops, air goes into the bottom side of the siphon tube and the whole thing drains which prevents it from restarting.



Does that help?

 

[SeattleReefer]

I've built 5 of these overflow designs based on that video. Works fine for me.

You problem is that the drain is at the same level as the lowest component and thus there is no trap to prevent a siphon break.

The drain line is supposed to be a little higher than the lowest part of the outside plumbing, thus preserving the siphon.

btw, Joey has an updated video with an improved design that has less pvc inside the tank.

FYI- this design is rather noisy. I had fun doing it but if I did it again I would go another route.

 

[vinxs]

Wow!! thanks for the responses guys,

That was the video i ended up going by.

I ran out of elbows to i used two tees, i was kinda leaning towards that being my issue.

Thanks heaps guys