Plumbing EXPERTS! Overflow question.

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aclockworkorange

Dovii
MFK Member
Jun 24, 2010
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Rose City
I've got a 225 gallon tank (72x30x24") with a overflow tower in the center of it. The bottom of the overflow is drilled for a 2" bulkhead. This tank is going to be in a house with no real room dividers (kind of a loft setup) so I will be able to hear it from my bedroom, living room, etc. and I don't want it to be loud. This will go down to and 80 gallon sump and pumped back into the tank.

The overflow tower is only 5x5" so there's really no room for a traditional herbie or even a standard durso--only a stockman. A friend of mine suggested doing a modified herbie by having the main drain be the bottom 2" bulkhead in the overflow with a standpipe a few inches below the water line (and a gate valve on that pipe below the tank) and drilling a second bulkhead in the overflow near the top on the back of the tank and having a 90 degree elbow facing upwards.

Would this work? Any other suggestions?
 
That should work. Just as long as you have the emergency bulkhead big enough to handle the flow of your pump. Keep in mind the elbow on the inside and outside will slow your capacity a little, so you might need to upsize.
 
So dual 2" bulkheads? Should I have the elbow on the inside? Should I do am external durso on the outside of the upper bulkhead or just a straight 90?
 
I think your friend is right ;)
 
If you can fit a 2" bulkhead, it can't hurt. More room to handle flow in case of an emergency. As for where to drill, you can put the hole anywhere along the back wall really. You would just need a PVC section to go up to where you spillover point will be.
 
Can you just put a strainer on that 2in bulkhead, and fill the overflow tower with bio-ball?
 
Here's a quick sketch of what I was taking about, just to make sure we're on the same page.

Height of the main drain: Wherever you want the water level in the overflow box to be. Higher = less splashing noise
Height of emergency drain: Wherever you want the max water level to be, so it won't go past this point

IMG_20111021_141851.jpg
 
Oh and forgot to mention, you could really put this emergency line anywhere in the tank, not just inside the overflow box.
 
Don't do a durso on the emergency. You need it sealed, because it should handle more flow that way. I was going to to suggest putting the emergency drain anywhere in the tank. I didn't know if was wanting the water level in the overflow to run about 4 inches low and have the emergency run one or 2 inches above that, but night right up at the brim of the tank. That way if there was an issue the emergency could get a good amount of water above it to create a good syphon if needed and flush the overflow back to the emergency drain level without being so nervously close to overflowing.
 
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