Silencing My DIY Non-AGA Overflow

[Frisco]

I know this question has come up numerous times, but I
could only find references to the noise problems
associated with AGA style overflows. So here goes...

I recently added a temporary sump to my 55 gallon reef
tank, using a Sen 900 as the return pump. I figure it's
moving approximately 800 GPH. For the overflow, I
drilled a hole in the side of the tank (approx 2-3" from
the top) and added a 1" SCH 80 threaded bulkhead. Inside
the tank, a simple threaded-slip ELL is used to collect
the surface water. A threaded-barb ELL is used with a
piece of flexible plastic tubing to couple the overflow
drain bulkhead to the sump. the sump sits next to the
tank, so the drain line runs straight down about 3.5 ft.
No gate valves are being used on either the return or
drain lines.

And I need to do something to silence this thing. It is
ridiculous how loud it is! I haven't been able to do
anything to reduce the amount of air being pulled down
the drain line. I certainly don't want to have to buy a
new tank with a conventional overflow box... unless I
have no good alternatives.

I have considered adding a second drain, enlarging the
existing drain to 1.5", and adding a valve to reduce the
flow. What have I failed to consider?


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http://members.xoom.com/FriscoReef/

[Agu]

You could try venting the air that is going down the tube along with the water. On the outside of the tank change the L to a T with the middle opening going onto the tank and the bottom draining to the sump. Cap the top and drill a hole Just big enough for an airline tube. I did this on my skimmer return line and it worked like a charm. This is just a variation on the "durso mod" Disclaimer: This is just a guess based on my experience. Be sure to check what happens if the vent hole gets plugged up, in an overflow it reduces the amount of water the overflow can handle (flood possibility)

[Larry M]

I think Agu has the right idea. I haven't personally tried this one but I have heard of it working well from several people. FWIW, 800 gph through one 1" line might be hard to quiet totally.
Good luck,

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Larry M

See my tanks at Northern Reef (http://www.reefcentral.com/northernreef/index.htm)

[Frisco]

I actually already tried it... By adding a 1.25" "T" with a short length of rigid 1/2" or 3/4" PVC for the vent and another 3.5' length of rigid 1" PVC for the drain... The outcome: my first experience with a flood! (I have hardwood floors in my apartment and don't consider losing my deposit an option; thank god I was watching and caught it within the first half pint...)

BTW - it was still loud... but at least it didn't sound like somebody slurping the last sip of a drink (through a straw) over a PA system. I mean, I can currently hear it in every room in the apartment, even with the doors closed. How loud are the problems with the unmodified AGAs?

So you guys are saying that I should simply be able to reduce the diameter of the opening for the vent to solve both the noise and potential flood problem?

[Larry M]

Yeah, and I know it doesn't make sense but it works. On my Durso pipes I have the top capped with a 3/32 hole drilled in the cap. When the cap is in place it works great. When I pop the cap off the water level actually rises, fast. You could try drilling a hole and cementing in an air valve so the level is easier to control.
I take it you have tried the old airline-stuck-down-the-pipe trick? IME these drilled through the back overflows are the toughest ones to make quiet.

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Larry M

See my tanks at Northern Reef (http://www.reefcentral.com/northernreef/index.htm)

[Agu]

Frisco, Did you have water coming out of the vent, or water and air bubbles like a protein skimmer? If it's air bubbles, capping it and attaching a piece of airline tube should allow the air to escape without taking water with it. Of course this could all be an exercise in frustration as you're moving a lot of h2o through one drain. Do you have a valve to reduce flow just to see if it's too much volume?

[Frisco]

I managed to fix the problem by adding a second overflow... Using a 1.5" bulkhead. I adjusted the height so that the 1" (the original one) serves as a backup if the primary (1.5") gets clogged for some reason. There's still a minor amount of noise, but this is managable. (I can sleep!) The original drain was way too small for the flowrate to work quietly. I'll continue to fool around with the vent idea to finish the job.

I cut back on my maxijets inside the tank. I now have the Sen 900 return running at about 800 GPH + three MJ1200 at about 300 GPH each run randomly by the Neptune. That's approx 15X per hour turnover between the sump and the tank and up to about a 30X internal circulation rate. I'm going to fool around with the programs to try and optimize the variation in flow inside the tank.

While I was drilling the tank, I started thinking about the 4 VHO bulbs I have sitting in my closet. And I got the urge to drill my hood to add 2 more VHOs. I have 2 50/50 and 2 003 110W bulbs, and my Icecap 660 is only running 2 4' bulbs currently. I should be able to get a shielded bundled cable from work on monday to get them wired up. I'll take pics of the tank with the two lighting combos... ie adding the 2 50/50s or 2 003s for a side by side color comparison.

And then I'll take pics of the overflow, skimmer setup, and my lighting upgrade saga and update my site. The new lights will place me on the high end of the lighting scale with 2 400W 6500Ks and 4 110W VHOs on a 55, and the increased color temp will probably look way better to the eye!