Issue with overflow drain pipe air hole

ACBlinky · 08/23/2008, 07:17 PM

I'm hoping someone can point me in the right direction, I'm at a loss.

The curved top of the drain pipe inside my 90g's overflow has a small hole (about the diameter of airline tubing) at the top, with a little piece of rigid tubing that sticks out.

In the past, things were fine, but now for some reason it seems that this hole is causing the water level inside the overflow to decrease by about 1.5". If I remove the tubing and block the hole with my finger, the water level goes down -- this leads me to believe that somehow the tube is blocked or not pulling in enough air, but it seems fine. I even replaced it with a new piece of tubing, but the problem remains.

The hole itself is clear -- I've cleaned it out with a brush -- and the tubing shows no blockage. Is it a bad idea to try and increase the size of the hole and use a larger piece of tubing?

My Remora HOB skimmer is on the back of the overflow, and the MJ 1200 pump pulls water from within the overflow -- when the water gets too low, the pump sucks air (this is what made me notice the issue in the first place). I can increase the length of the hose that connects the pump to the skimmer, so it's further down, but I'd really like to just solve the issue at the source since I have a feeling it's not something I should allow to continue.

Thanks guys!

brians4671 · 08/23/2008, 10:08 PM

this hole is causing the water level inside the overflow to decrease by about 1.5". If I remove the tubing and block the hole with my finger, the water level goes down

sounds like it goes down because it is syphoning instead of draining like it is designed to do. is this possible?

crvz · 08/23/2008, 10:33 PM

there shouldnt be any issue with redrilling the hole larger, but why don't you take the time now to redo the standpipe? Do some research and look around at different options, it's rather inexpensive to build a new one all together.

08/23/2008, 07:17 PM	#1
ACBlinky Premium Member Join Date: May 2005 Location: Peterborough, ON, Canada Posts: 4,954 Blog Entries: 20	Issue with overflow drain pipe air hole I'm hoping someone can point me in the right direction, I'm at a loss. The curved top of the drain pipe inside my 90g's overflow has a small hole (about the diameter of airline tubing) at the top, with a little piece of rigid tubing that sticks out. In the past, things were fine, but now for some reason it seems that this hole is causing the water level inside the overflow to decrease by about 1.5". If I remove the tubing and block the hole with my finger, the water level goes down -- this leads me to believe that somehow the tube is blocked or not pulling in enough air, but it seems fine. I even replaced it with a new piece of tubing, but the problem remains. The hole itself is clear -- I've cleaned it out with a brush -- and the tubing shows no blockage. Is it a bad idea to try and increase the size of the hole and use a larger piece of tubing? My Remora HOB skimmer is on the back of the overflow, and the MJ 1200 pump pulls water from within the overflow -- when the water gets too low, the pump sucks air (this is what made me notice the issue in the first place). I can increase the length of the hose that connects the pump to the skimmer, so it's further down, but I'd really like to just solve the issue at the source since I have a feeling it's not something I should allow to continue. Thanks guys! __________________ "The cure for anything is salt water: sweat, tears, or the sea." - Isak Dinesen Current Tank Info: 150g mixed reef, 30g sump/refugium, LED lighting, 100lbs LR, coral beauty, flame angel, blue & yellow tangs, gobies, damsels, 6-line wrasse, lawnmower blenny, dottyback, clown pair, rabbitfish, shrimp, crabs, CUC.

08/23/2008, 10:33 PM	#3
crvz Team RC Member Join Date: Jul 2005 Location: houstonia Posts: 7,989	there shouldnt be any issue with redrilling the hole larger, but why don't you take the time now to redo the standpipe? Do some research and look around at different options, it's rather inexpensive to build a new one all together. __________________ -Chris- You don't win friends with salad. "Look! They're trying to learn for free!" ... "Use your phony guns as clubs!" Current Tank Info: rectangluar? wet?

08/23/2008, 10:08 PM	#2
brians4671 Registered Member Join Date: Nov 2007 Location: miami fl Posts: 2,088	this hole is causing the water level inside the overflow to decrease by about 1.5". If I remove the tubing and block the hole with my finger, the water level goes down sounds like it goes down because it is syphoning instead of draining like it is designed to do. is this possible?