Noisy Gurgling Overflow - SOLVED!!!!

[Ron99]

I am still fiddling with this 75 gallon tank. it has a single overflow in the upper left corner. It's a 1.5 inch bulkhead and I've got an external Durso type of arrangement. The T section is made of 1.5" PVC. I have a short length of 1.25" hose and then it is reduced to 1" hose. I cannot get this to be quiet. It gurgles loudly all the time. I have tried using everything between 1.25" hose to 0.75" hose down to the sump. The 0.75" hose made it fairly quiet if I pretty much maxed out the flow so almost no air was going down the line but then I worry about something further reducing the flow down the line and ending up with the tank overflowing. I have also tried numerous hole configurations and sizes in the cap at the top and also putting airline down to various depths. Nothing works.

I hope somebody has insights into setting up an overflow with only one drain of this type.

Here's a pic:

[dkcrx]

have you tried useing hard line (pvc) to the sump?
I have mine set up that way, and remove the air line from the top of your pvc cap, mine only makes noise when the small hole in the cap starts to plug with salt, acts as a warning to clean it out.

[fkshiu]

Some suggestions:

- as mentioned try using a hard line all the way down to the sump
- using a sanitary T (I know, they're hard to find in PVC) would help
- tap some threads into the hole at the top and screw in a JG ball valve.

I think the final suggestion would have the most effect because a Durso is all about controlling the amount of air that gets mixed with water. With the ball valve you'll be able to do that. I remember back in the day (waay back) when Wendell at OA first showed me how his Dursos worked with ball valves controlling air intake.

[banditpowdercoat]

Your vent hose is to large in Diameter. It's not matching the drain size to the cap hole, but matching the cap hole to the flow requirements. I have 6 0.018" holes in my cap for venting, about 300GPH drain. and it's silent. Try getting a shutoff on the vent, something you can precicely throttle back untill it's silent.

[mark]

Originally Posted by banditpowdercoat

Your vent hose is to large in Diameter. It's not matching the drain size to the cap hole, but matching the cap hole to the flow requirements. I have 6 0.018" holes in my cap for venting, about 300GPH drain. and it's silent. Try getting a shutoff on the vent, something you can precicely throttle back untill it's silent.

found with my 2" Dursos running between 500 and 1000gph, hole size in each is only around 1/8"

[Tom R]

I find that using Spaflex tubing helps muffle the sound. Spaflex tubing is available at most Hot Tub stores if they do installation.

Tom R

[Ron99]

Thanks for all the input. I have tried to replicate the valved vent by drilling a larger hole then taping it closed and using a pin to slowly enlarge a hole in the tape. All it does is affect the height of the water in the overflow box but little to quiet the gurgling. I'm not sure using solid pipe or spaflex will help muffle noise as it seems to be the gurgling of air at the T that is then being amplified in the T itself and sounding loud if that makes sense. But I may give it a try.

dkcrx, it looks like you have your pipe at about a 45 degree angle. This is why I used flexible tube as I need to go to the opening in the stand that is in the middle but the overflow is on the side. So I may need to angle the pipe as well and then use a couple of 45 degree elbows to get into the stand and sump. Would you mind posting a picture of the your configuration at the sump as well?

But as I said, most of the noise seems to be the gurgling at the T where the air/water interface is fairly turbulent and alot of air is being sucked down into the plumbing.

[Ron99]

Also, do you guys run the same diameter pipe all the way down from the bulkhead or do you decrease it at some point?

Thanks.

[whatcaneyedo]

Your overflow looks like mine... I've got some time off coming up soon so I'm just going to put everything from my display tank into the sump and bring the tank into a glass shop to get a second hole drilled for a herbie style overflow.

[dkcrx]

Originally Posted by Ron99

Also, do you guys run the same diameter pipe all the way down from the bulkhead or do you decrease it at some point?

Thanks.

Same size all the way to the sump, and I have one 90deg turn in the pipe