Herbie style overflow

[mark]

On you main drain have you tried removing the 90° or having the opening facing the top?

If you have and you finding it sucking air, option is to redrill on the side, just lower down right towards the bottom (immediately below existing main), then place the upturned 90°. The original main drain then could be either plumbed back as another emergency or blanked off.

Can also give up the idea of the Herbie, and run a external Durso. On the main, leave the 90° pointing down, on the outside of the tank have a tee. Cap the top, then drill out for the air (starting will a small bit, or tap for a air valve), the downward leg to the sump.

[Chad]

I removed the 90 from the drain already.. so it is just the bulk head.. I love how silent it is right now, just wish I could get it to restart on its own.

The whole problem is that it will not restart after a power shutoff and almost all the flow goes through the emergency drain. I am sure if left for hours the air would work its way out of the main, but that is just silly..

[mark]

you realize though depending on how closed the valve is on the primary drain is, the water will back up over the top of the primary.

On my 33g will about 200gph, with everything balanced (surface height steady) the water surface was over 2" above the top of the drain.

Might need also to increase the height of the emergency.

[Captainhemo]

Hmmm, if its actually airlocking, you should be able to drill a small " bleed" hole right above the water line where the drain enters the sump

[Chad]

would that still work if you have the gate valve? should the bleed hole be before or after the gate valve?

[Captainhemo]

Well, this wouldn't be a "normal " placemnet for an air bleed, I'm kinda hoping it might work though....
I'd try putting a small hole right above the water line of the sump (between the water line and the bottom of the gate valve) .