So, you know when you put the weir on and the water flows into the box that flows into the refugium. What keeps the water, when the power fails, from siphoning into the refugium and emptying the tank all over your floor?

Thanks,
-Stu

I don't know the weir thing... ? :unsure:

This thing

Or this one (better picture)

-Stu

Acutally... looking at that picture it looks like that if the water level in your tank went down, it wouldn't suck anymore up, but it wouldn't loose it's siphon.

Exactly. It's simple physics. Once the water level falls below the intake or "overflow" it's impossible for it to drain the tank. The key is to have a sump big enough to hold the amount of water that would be lost during a power outage. To know that precisely just figure the L and W of the tank and the depth the water must drop before the siphon stops. IE if your tank was 24"x48" and the water dropped 2" before stopping you would need a 10 gallon sump. Be sure to figure in at least a 25% safety factor and plan accordingly.

How do you start a siphon on that, though?

To start my siphon off (freshwater trickle filter), I close the valve and let the siphon tube fill with water. Then I turn the valve back on and I have a siphon going. :)

I dun the smart thing and bought a UPS for my tanks, best thing I ever did, They turned off our power one day as a mistake and that UPS kept things goin for about 2 hours (minus the overhead lights) till the power company turned us back on, I would Reccomend doing this