Question on Herbie method, E drain height and water level in overflow

[AUFishGuy]

I have a 90 gallon reef ready and I am running the her big method. The top of my E drain sits just below the top brim of the overflow with a light trickle.

When looking at articles and pictures of the Herbie method it is suggested that the E drain be 1/2"-1" below the grates on the overflow. I am confused by this. If this were the case wouldn't the water level in the display just stay at the bottom of the grates and no higher? I feel if that's the case that is a lot less area for detritus and the like to make it into the overflow and into the sump as well as leaving a lot of room in the tank without water. Am I missing something here?

 

[thegrun]

The water level in your display tank when the return pump is on will likely be about 3/4" to 1" above the bottom of the slots. I set my emergency drain at about 1/2" above the bottom of the slots, but you need to have the emergency drain at least 1" below the top of the tank so it can pull a full siphon if the need ever arises. You want the running water level in the overflow box to be slightly below the bottom of the slots so it pulls surface water into the overflow box but not so low as to cause noise from the water falling into the overflow box.

 

[AUFishGuy]

The water level in your display tank when the return pump is on will likely be about 3/4" to 1" above the bottom of the slots. I set my emergency drain at about 1/2" above the bottom of the slots, but you need to have the emergency drain at least 1" below the top of the tank so it can pull a full siphon if the need ever arises. You want the running water level in the overflow box to be slightly below the bottom of the slots so it pulls surface water into the overflow box but not so low as to cause noise from the water falling into the overflow box.

Isnt the height of the E drain going to set the the level of the water in the DT. If the E drain is half way up the grates the water in the DT will be halfway up the grates. similarly if the E drain is below the slots the water in the DT will never be above the bottom of the grates?

Correct?

 

[cmbspd]

for a herbie, the emergency drain sets the water height. you can make minor adjustments to the height if you have some sort of moveable top on the emergency pipe. In my old setup, I put a PVC coupling at the top of my drain pipe that I could slide up or down about 1/4 inch (it helped to finely tune my final water level without switching out the whole pipe)