120g overflow plumbing help

Flynsqwirl · Jun 5, 2025

I have a tank I'm setting up and it has one 2" and one 3/4" for overflow into the sump. Should I use the 2" and choke it down with a gate valve or use that as the emergency and use the 3/4" on a gate valve? These gate valves are pricy and hard to find in that size. TIA

tbrown · Jun 5, 2025

For a 120 I'd think the 3/4" would be a small drain. My 70 uses a 1.25" drain and 1.25" emergency overflow. It uses a 1" return.

If they're both drain pipes I'd consider the 3/4" with the gate and the 2" as the emergency. If it backs up, I'd want to make sure my tank doesn't overflow.

Flynsqwirl · Jun 5, 2025

tbrown said:
For a 120 I'd think the 3/4" would be a small drain. My 70 uses a 1.25" drain and 1.25" emergency overflow. It uses a 1" return.

If they're both drain pipes I'd consider the 3/4" with the gate and the 2" as the emergency. If it backs up, I'd want to make sure my tank doesn't overflow.

That's what I was thinking of doing. 3/4" is pretty small but that's what I got. It was originally set up using two 3/4" external returns into the tank and the 2" as the drain and the other 3/4" going into the internal overflow box that was drilled out on each side with return heads. I plugged them up as I'm worried about check valves and the whole tank draining. I can't imagine how load a 2" drain going straight into the sump was with that setup.

tbrown · Jun 5, 2025

Flynsqwirl said:
That's what I was thinking of doing. 3/4" is pretty small but that's what I got. It was originally set up using two 3/4" external returns into the tank and the 2" as the drain and the other 3/4" going into the internal overflow box that was drilled out on each side with return heads. I plugged them up as I'm worried about check valves and the whole tank draining. I can't imagine how load a 2" drain going straight into the sump was with that setup.

I have my ball valve closed a little over halfway to keep the noise down.

UncommonSense · Jun 5, 2025

Flynsqwirl said:
That's what I was thinking of doing. 3/4" is pretty small but that's what I got. It was originally set up using two 3/4" external returns into the tank and the 2" as the drain and the other 3/4" going into the internal overflow box that was drilled out on each side with return heads. I plugged them up as I'm worried about check valves and the whole tank draining. I can't imagine how load a 2" drain going straight into the sump was with that setup.

Is the 3/4” bulkhead PVC? Or ABS? You might be able to sneak a thinner 1” ABS bulkhead into the 3/4” bulkheads drilled glass hole!

Flynsqwirl · Jun 5, 2025

tbrown said:
I have my ball valve closed a little over halfway to keep the noise down.

With 3/4" with dual 3/4" returns idk if it would be closed at all

Flynsqwirl · Jun 5, 2025

UncommonSense said:
Is the 3/4” bulkhead PVC? Or ABS? You might be able to sneak a thinner 1” ABS bulkhead into the 3/4” bulkheads drilled glass hole!

Idk, I just ordered a new bulk head from brs and it came in today. Im not sure what it's made out of.