Sump and Overflow

[Akraziatic]

Okai I've got all the sump plumbing done...

Got it all going.....

but then the siphon doesn't seem to keep in the overflow box.

It keeps it for a bit but then after about 30 or so seconds it stops.

Would I be right in thinking that the overflow box isn't level therefore I can't suck all of the air out and the left over air in the siphon is causing the siphon to break???

Any help will be muchly appreciated..

I need to set this tank up asap

Cheers

 

[dw1305]

Hi all,
Akraziatic it probably just needs a little breather hole at the highest point of the syphon, any air bubbles etc that get sucked in will then be vented of from the hole, and this stop them forming an air-lock.
cheers Darrel

 

[Akraziatic]

The air getting trapped is from when I try and suck the air out from the siphon. Its not so much the air coming through the siphon but what I can't get out because its off level.

Will an air lock cause a siphon to break?

 

[Rabbit]

Have you checked the venturi is open?

 

[Akraziatic]

Okai does anyone know how to get the venturi to work coz its just not keeping siphon!!!

 

[dw1305]

Hi all,
Akraziatic you need to check that the siphon pipework hasn't got a leak that is letting in air somewhere?, usually at the joints. If it's air tight as long as the bottom side (where you are siphoning too) is lower the siphon will keep going, as yours is down to a sump that can't be the problem.

If the syphon picks up air bubbles from the tank, over time these will rise to the highest point of the pipework, and eventually form an air lock, this is why you need the breather hole (or the venturi tube open).

Here is a simple design (without an overflow box), it works fine.
<http://www.aquariumlife.net/projects/diy-overflow/120.asp>

cheers Darrel

 

[dw1305]

Hi all,
Sorry re-reading the post I think I've got the answer, you are saying that the tubing is not level, so that the venturi/breather hole is lower down than the highest point of the syphon pipework?

In that case it won't syphon continually, because an air lock will form at the highest point, where you can't vent it away. If the difference between the highest point and the venturi is more than the internal diameter of the pipe? then it will stop very quickly as air will come in and fill the entire section of the pipe (above the venturi), causing an air lock.

If this is right you need to either level the pipe work, or fill the hole you've got at present for the venturi/breather hole and move it to the highest point of the syphon.

cheers Darrel

 

[Akraziatic]

I've got one of these:

http://www.guppysaquariumproducts.com.au/protein-skimmer-overflow-box/overflow-box/overflow-box-flowrate-is-5000/prod_1139.html

I've tried starting the siphon but the grey bits on the end of the airline tubing are letting air back into the siphon.

It's not so much air bubbles over time. It's all happening within a maximum of a minute.

 

[Akraziatic]

Thanks Darrel. I had pulled the tank apart today and levelled the stand again as it wasn't level where I had put it. So I've ruled that out. It seems to be in the actual siphon.

 

[Rabbit]

LMAO, I take it generally these box's link to a powerhead in order to make the venturi work huh?.

 

[Akraziatic]

Yeah I'm giving it a crack with my aquaone filter which has a venturi nozzle. But there still seems to be air getting in :S ACHK!!

 

[Akraziatic]

Nah fail. siphon broke...

 

[Lornek8]

Unless I am looking at it wrong, those tubes on top are to vent out any air and start the siphon. Once the siphon is started the tubes should be plugged so that no additional air gets back into the siphon. There shouldn't need to be a powerhead or anything fitted to the siphon box.

 

[Akraziatic]

Yeah that's the way I saw it aswell. However the siphon dosn't hold. I've read on some marine forums that they do hook the air tubing up to the venturi on powerheads or use a vacuum pump to keep the siphon going. But one would imagine that this wouldn't be necessary.

 

[Lornek8]

Is this a popular model in Australia?
Seems to be a poor design if enough air can get sucked in(?) to break the siphon. Almost appears as though the overflow box is too small.
How about stuffing filter floss in the overflow box to break up the air bubbles?

Edit: Could you contact the supplier to get their take on the matter?

 

[Akraziatic]

nah not sure.. theres not many around...

it dosnt break the siphon imediately but slows the flow rate down so much and then eventually breaks it.

I hope its not too small as its 5000LPH and the biggest I could find.

mmm thats an idea..

Yeah I should get on to them.

However I've fixed the issue by using the venturi's on two powerheads to keep the sucking the air out. they end up pulling a little water but not enough to obstruct the siphon..