Plumbing Hole Distance

[Protodad]

So I happened to get a smoking deal on this 120g tank. It came pre drilled with a 1” and 3/4” hole behind the overflow. I’m 90% sure it was set up to be a 1” drain and 3/4” return as the overflow has a return hole in it.

I’d like to run it as a Herbie style overflow but due to some space constraints I can’t run a return pipe behind the tank without going into the wall.

I was playing around with spacing for a 3/4” bulkhead as shown in the pictures. Just looking for some thoughts on if the holes are too close together. I’m comfortable with drilling it, but I don’t usually have the space constraints this tank will have.

 

[tfeeken]

I picked up a tank like that and actually cut out the internal overflow, sealed off the holes in the bottom with another piece of glass and plumbed an external overflow and return lines. So much happier with the amount of internal space and no need to scrape coraline off a plastic overflow in the future.

 

[Protodad]

I picked up a tank like that and actually cut out the internal overflow, sealed off the holes in the bottom with another piece of glass and plumbed an external overflow and return lines. So much happier with the amount of internal space and no need to scrape coraline off a plastic overflow in the future.

That would be the preferred method for sure (I just drilled an external for another tank. Unfortunately, this tank is 24” deep and going in a 24” deep opening. No room for an external overflow.

 

[resortez]

I’ve owned several tanks with the exact same set up & have had success with them. In my experience, I’ve never had issues running a 1” drain with a 3/4” return all within the overflow box. I do recommend valves on both the drain & return if the pump is not controllable, along with a dorso pipe. Because of the return nozzles coming out the box, you will need to add more loc-line extensions so the returned water doesn’t get immediately sucked right back in into the overflow, if that makes sense. Good luck & hope it helps.