overflow

[noobtank]

Grr...well i feel like a big noob now. I have everything set up except for how do i get the water from the hob overflwo to work. i can't get the thing to siphon.

[dizzyliz]

i put air line tube up into it and sucked

--Liz

[noobtank]

while the u tube is in the water?

[RMPD109]

Fill both sides of the overflow with water. Put your U tube in place. Use the airline tubing to fish one end into the top of the U bend. Suck out all the air from the top of the U bend. Your siphon should be good to go.

[ellisz]

Yes. Put a small air line tube up into the U at the top. Turn your pump on and then suck into the air line tubing. This will start the siphon. Suck real hard to you remove any air in the U tube.

[noobtank]

omg thank you so much....ur a life saver...i finally got the plumbing right..yay

[jaiden]

Keep in mind what will happen to your tank if the power goes off, the siphon breaks, and then the power comes back on. there are "aqualifter" pumps which are cheap, and built to draw out this bit of air in such an event.

Try to think of all the failure modes in your setup. Do you have enough room in your sump that if the return pump fails, it won't overflow? What if a snail crawls onto your overflow tube?

[dralarms]

there are "aqualifter" pumps which are cheap, and built to draw out this bit of air in such an event.

Can you provide a link? I need one big enough to handle 2 overflows.

[ellisz]

If the U tube is done right, it should not lose siphon when the pump stops.

[tripper]

If the power is out for an extended amount of time, the main will drain into the sump until the siphon is broken because the water level is too low. The problem arises when the power comes back on and the pump returns water to the main but there is no siphon in the overflow.

The result. . . water everywhere until the sump is dry.

I'm tagging along too, would like to find out about the aqualifter pump

[RMPD109]

your overflow box will never run dry. As the tank volume lowers it will stop adding to the overflow but it will retain water in both chambers and the U tube should hold its siphon. The only siphon that will break should be back siphoning in the return tube that goes from fuge to tank.

[dralarms]

Mine has never lost siphon, however it does collect air in the center so I have to siphon it out. If I had a pump to do this I could save me breath for more important things .

[ellisz]

If the siphon holds the water should push the air out when the pumps starts back up. Really if there is not air in it to start and the water level in the overflow is where it needs to be, air should not be introduced.

That being said, I did a DIY overflow box and always fought with it. I hate HOB overflows.

[Brad]

If the power is out for an extended amount of time, the main will drain into the sump until the siphon is broken because the water level is too low.

Not true with a well designed overflow, Trip. What you describe would happen if the overflow was just a simple "U" shaped siphon...but most are not.

A well designed overflow has 2 chambers, one on each side of the siphon tube. These chambers never empty, regardless of what happens to the tank level. As long as these chambers and the siphon remain full of water, the siphon will restart as soon as water starts to flow again.