Sump help
 

Well I finally got it built 29 gallon tank with a 20 Gal sump using the HOB PVC overflow. Everything is working well. I tried stopping and starting the pump and it starts up right away. Tank stays full from the overflow.

Now onto the problem. When I turn off the pump, the water from the tank drains back through the pump. Ant ideas on how to stop it from doing that? is there some sort of anti siphon valve out there or what?

Thanks in advance. I can post pictures if anyone is interested.

Glenn

The best strategy is to have a big enough sump that it will catch your backflow but there are a couple things that you can do.

You can get a check valve which is a little piece of gear that goes into the return line between your sump and the tank, it only allows water to go one way and so it functions as your anti siphon. The problem is that it isn't a question of if this thing will screw up but when, the answer usually being at the worst possible time. Not advisable to rely on it.

The second thing you can do put a siphon break in your return line. This is a little hole that is punched in your return just below the normal water level, small enough that it doesn't have a lot of water going through it. When the pump shuts down the water level begins to drop but when this hole is exposed you get some air sucking through the hole and this breaks the siphon. Problem is that when you really need it to work there will probably be a chunk of debris that covers it or a snail parked on top of it or some other stupid thing. You can mitigate this by making a few holes but again it's not really a great idea to rely on it.

If you can't change your sump you'll have to figure out what level of uh oh you are willing to live with.

There's two ways to deal with this... the expensive unreliable way is to buy a PVC one way check valve that will almost certainly fail eventually or you ca simply raise your return line to a level just below the tank water level so that when only a small amount is siphoned out of the tank and into the sump air will fill the line and break the siphon.

Loc-line is a great option for getting the level just right.
You can Y it off and have one pointed down to add flow to the tank and one just under the water level for surface agitation.

Sorry to sound dumb but what exactly is locline? I see never mind. Google is my friend. Now the only question is whre can I get locline and adaptors to go to 1/2 inch pvc in town here?

Thanks:razz:

Well, where is town? :wink:

OOOOOOOOPpppppppppsssssssss. Town is Calgary. I thought it showed on my sig. Sorry

Go
 

Here's a shot of a returnline set at the waterline level. If the pump stops it only backdrains 1 - 2 gallons.
http://i35.photobucket.com/albums/d1...r/100_0731.jpg
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Honda VTX1800T

Thanks What is the black part that you have on the outlet end? Just a strainer?

http://www.oceanaquatics.com/images/...20category.JPG

I'm not sure where you can get it local,
But Ocean Aquatics carries it on there web page
http://www.oceanaquatics.com/index.php?cat_id=91&catname='Loc-Line'
It comes in 1/2' so no problem there.
The adpater screw's into threaded PVC.
There is a special tool for working with the stuff. Makes working with it a lot easier but you can mange with out it.