Reef central sump volume calculator

[Entertainer]

i used the reef central sump volume calculator and it says "Sump Volume need to handle tank overflow = 4.8 Gallons" based on 2" of water height above overflow. does this mean that my return section alone must be more than 4.8g?

or does it means the whole sump will take an extra 4.8g of water if the pump is cut-off?

 

[tzylak]

In layman's terms, the sump must accommodate all the water that overflows from the DT wile all pumps are off. -In case of power outage the sumps accepts all the overflow water without spilling out.
In other words, the sump is not intended to be full during the normal running time.
The 2" water drop is just an arbitrary number. -My DT water level drops 1.5". . .

 

[thegrun]

I like to size the return section large enough to handle all the drain down water if cabinet space allows. If the drain down water fills the return section and then starts to increase the water level in the refugium section or the skimmer sections it may cause the skimmer to overflow and when the refugium overfills macro algae may be sucked into the return pump.