sump return/flooding precautions

[Statman]

I was reading on Melev's Reef site that I should drill to 2holes in my return line. Im a little confused as to how this is going to help. If the pump is still on, its gonna pump water up regardless of the holes. Or is he saying that incase the pump fails, the holes will stop the water goin back? If thats the case, he is saying that if the pump quits, water will still return to the tank via a siphon? And these holes, would kill said siphon?

I just wanted a little clarificaton before I go drilling holes.

 

[almo75]

If the pump stops and drains the tank it may siphon down the return line too. Those small holes will act as a siphon break. Just visited that site yesterday and did some reading.

 

[Statman]

i still dont understand. you say if the pump stops and drains the tank, well if it stops how is it gonna drain the tank?

 

[Sploke]

The holes are to break a siphon on the return line BEFORE it drains the tank. If hte pump stops, water can siphon backward down the hose, through the pump and into the sump. A small hole right about at water level will break this siphon before too much water makes it down the hose.

 

[Statman]

so if im getting this, when the pump quits it may start a reverse siphon, sucking water from the display tank down into the sump, which would eventually flood? thats what your saying?

 

[Fishieness]

so if im getting this, when the pump quits it may start a reverse siphon, sucking water from the display tank down into the sump, which would eventually flood? thats what your saying?

It might flood. It depends how far down your nozzles are in the water and how much extra space you have in the sump. It isn't needed or even helpful on all systems.

 

[Statman]

thanks for the clarification. my return nozzle is quite high, i wont have an issue. =]

 

[kcress]

so if im getting this, when the pump quits it may start a reverse siphon, sucking water from the display tank down into the sump, which would eventually flood? thats what your saying?

Yes exactly what is being said! You will have the sump level rise when the power fails. Always. How much depends on how big the lines are and how low in the main tank these lines are set and whether you have a functioning siphon break or not.