New sump ???`s

[panmanmatt]

To start the siphon in the U-tube you need to insert the airline in through the bottom of the tube all the way up to the top of the U. Once there, you need to suck out the air until the whole tubes is full of water. This will start the siphon when you turn the pump on.

The siphon break hole in the return line is to allow air into the return when your pump is turned off. This will stop your whole tank from draining back into the sump. If it's not working that way, you may need to either increase the hole size or drill another one to allow more air in.

[PEMfish]

So if I empty the U tube of air, it won't drain the over low and then loose the water in the U tube ( assuming the overflow is not able to draw water. )?

[panmanmatt]

It shouldn't. You can also hook an Aqualifter pump to the airline you place in the U-tube this way it will automatically restart the siphon in the event of a power outage.

[tbittner]

hmmmmm.....

If the pump isn't running then the water from the tank should drain down until it's at the level of the baffles in the container that is outside the tank. The outside container should have a baffle in it that stays full of water. As the water rises in the tank, the siphon sucks the water out of the tank and overflows that baffle into the compartment that the drain pipe is connected to.

If the size of the baffle is equal to or higher then the edge of the inside container then the siphon should never get broken unless the pump doesn't run for a very long time (weeks).

[tbittner]

Originally Posted by PEMfish

Got the tank from Rod. In great shape for an used one.

For the overflow, I was thinking this: (see pic). I know that will create a reliable flow, wont it? Is it looking good? I won't be doing a good looking acrylic job, just something that works. I will also have a tube connected to the top of the U tube to prevent air build up.

Reading back, the tube needs to be air tight. No air in, no air out. Do you have a tube at the top of the U tube?

[tbittner]

A pic of your overflow would really help us all to be on the same page.

[PEMfish]

The wall baffle is lower than the overflow.
I'll get pics latter.

[tbittner]

Both ends of the U tube have to stay submerged at all times in order to maintain the siphon. Fill both boxes with water, insert the air line tube up into the U tube, all the way to the highest point, and SUCK!

Sorry...

You'll suck all the air out and the U tube will fill with water and the water level will drop until the level in the skimmer box equals the height of the baffle wall in the outside box.

[PEMfish]

But the overflow in the tank is a good 4" above the baffle. So when I suck the water flows to the HOB. Then, it either starts flowing down to the sump, or if there is no more water in the tank to replenish the overflow the U tube sucks air . Either way, its a no go. I'll try again.

[PEMfish]

fallow the arrows in order and you should be able to figure it out.

[tbittner]

That's your problem right there. The baffle in the outside container needs to be high enough that it holds enough water so it's at the level you want to keep the water at in the tank when the pump isn't running. Both ends of the U tube MUST stay completely submerged at all times.

As the water level rises in the tank, it gets higher then the water contained in the outside container. The siphon starts to suck water into the outside container, raising the water level in it. It overflows the baffle and flows down the drain. The higher the water level rises in the tank, the faster the flow will be through the U tube.

When the pump is turned off, the siphon will suck water out of the tank until the water levels are equal in the skimmer box AND the contained box in the ourside container.

Simple test, make the baffle in the outside box higher.

[PEMfish]

The outside box id 1" lower than the rim of the tank.

[tbittner]

The top of the box isn't important, it's the top of the baffle that will keep water in that compartment that's important. The water level in that compartment needs to stay high enough to keep the end of the tube under water.

You can try to lift the box up a few inches, which in turn will raise the top of the baffle.

Or you can make a new U tube that is long enough to reach close to the bottom of the compartment with the baffle. That will work too. Just know that when the pump is turned off, the siphon will lower the water in the tank to the same height as the top of the baffle in the outside box

[PEMfish]

Both ends of the U tube do stay under water.

[Woodstock]

PEMfish - here is a photo of the external overflow box that is on my hospital tank. This pic was with the return pump OFF; the water on both sides reached equilibrium and the water flow through the Utube stopped. No air gets in the Utube.