Terrible Advice Tuesdays (T.A.Tues): A Durso Overflow Can’t Be Quiet

Terrible Advice Tuesdays: (T. A. Tues): Durso overflows are loud and can never be quiet.

The rest of the story: Every time I hear this piece of terrible advice, I want to dial one of my tank build clients and have them hold their phone up to their overflow because I know that their durso overflows are quiet.

The truth is that a durso overflow can be just as quiet as any of the more complicated “noise busting” overflow designs if you design and setup your durso correctly. (For those of you that have my No-Nonsense Guide To Setting Up A Saltwater Tank, Vol 1, see the Durso Overflow video for a full explanation)

One of the several important steps of a quiet durso design is the rate of water flowing through the overflow. Simply put, more flow through the overflow equals more noise. And the biggest factor for determining flow rate through the overflow is the flow rate of your return pump. A high-flow return pump invites more noise into your system and the overflow is one of the first places you’ll hear that noise. Keep in mind this fact is true for any overflow type. I’ve been around nearly all the overflow types and high water flow through a pipe means more noise every time.

When you are setting up your saltwater tank, or if you already have your tank setup and you have a noisy durso overflow, check your return pump rate first. The noise problem might not have anything to do with your overflow.



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Comments for this article (23)

  • Massimo says:

    Hey Mark, great tip. I have a couple questions to ask you regarding my current aquarium build. Can you help me? Do I email you privately? Thanks!

  • Stu says:

    I use a Durso and it’s as quiet as a mouse, 200 litre tank with 3,000 LPH return on the pump with the water level controlled in the Weir by a valve on the bottom weir return pipe. I can then control the level in the weir and the amount flowing through the top and bottom to get a almost silent weir. On top of this, to reduce noise in the sump on the return pipes, I use filter socks by Bubble Magus. Not only do they trap a lot of the detritus coming from the tank before entering the sump, but also acts as silencer for the water flowing back into the sump from the durso.

  • dave says:

    hello marc. I was watching a bit you have posted on youtube about ph and putting your intake pipe outside I see you say to put it thru the side of the house. one problem 9and probally the biggest) is if the power goes out and the line is below the tank you could empty out your system causing all kinds of trouble. ie temp probe above water line causing over heating etc etc. so make sure it is above the water line

  • Keith Hays says:

    I 100% agree with this, I have Dursos running in two different tanks my system in my living room and I don’t hear them at all. What I have noticed is the primary reason people tend to hear any kind of gravity overflow is that their overflow pipes are too small for the amount of water they want to move (and they quite frequently want to move too much water). 1″ pipes in overflows should be banned in all but nano tanks; they simply can’t move enough water to be useful without a full syphon.

  • Ok so please try this. I built my durso out of 1″ PVC if you put a cap and drill a hole in the top 1/4″ only, then get some RO line about 6-7in. long. With the tank running, shove the RO line in untill the noise stops. I’ll say about 2in. Of the line will be sticking out of the top cap. This lets the air flow right on down with the water.

  • Adam Baggett says:

    I use a Durso on my overflow and I have no noise. I control the flow from my return pump with a valve and have taken a lot of time tuning it in. I also agree with @AronLockhart I have put RO line down the Durso and played with it also.

    Great tips…..

  • Sami says:

    My overflow could not fit a Durso. So I used a Stockman. An excellent alternative

  • Hector says:

    My problem with noise is always at the sock, this is where all the air escapes and with it the noise.

    Haven’t figured out this just yet, I just dialed down the flow rate but now I feel that I am not getting enough filtration.

  • @hector Like I mentioned above. try the RO line or air line. Put the pump on 100% output

  • Nik says:

    I run 1 inch line on my overflow. I set the system up and it is quiet. I put an elbow on the drain inside my overflow, and always run full siphon (after all, siphons work beat when full) takes some time to tune, but when done, it is silent. In the sump I leave the drain line 1-2 inches below the water level.

  • Hector says:

    i have the air line in the overflow, its very quiet, no noise at all but all that air that is sucked in escapes out of the drain in the sump which causes a lot of noise.

    I added a 1″ pvc pipe so that it drains under the water line but it didnt help as all the air escaped with force. I added holes and slits so that some of the air escapes before draining but like I mentioned before, I lowered the flow to reduce the noise.

    Anyone try adding a air line at the elbow of the drain? I havent as I dont know if that would work.

  • Forrest says:

    Make sure the holes start above the water line in your sump.

  • 915Mang says:

    Very true, My Durso is silent! Youtube 915Mang, also gooe durso standpipe. Theres a great website

  • RLD says:

    I decided not to go with the normal drains and durso and went with a straight drain pipe with 2 backup straight pipe overflows for safety. Some call this a “Herbie”. The drain is silent as the water completely fills the drain pipe and creates a total vacuum. The Herbie offers one extra drain but I have 2 for total safety.

    With this method, there is no gurgling, splashing and the flow can be much greater than with a durso and air running through the drain and best of all, it is dead silent.

    However, as Mark states, a low flow durso drain can be quiet also, but if you want more flow, a Herbie type is a good way to go.

    Mark, I want you to know that I have really appreciated your efforts in helping others with reef aquariums, and hope you will continue for many years to come. This hobby needs good information and you go out of your way to get the information and to pass it on to others.

  • Kenneth Baez says:

    I wish my tank was drilled for many reasons. However, as far as quite goes mine is quieter than the accused in church.

  • Ted says:

    What is your opinion about the Bean Animal overflow with 3 drains?

  • Ted says:

    Sorry Mark I meant Herbie.

  • Buddy says:

    I’ve never really given much thought about drain noise.. I actually like hearing the sound of running water, it’s like resting or camping near a small running stream and can be quit soothing.

    My 120 corner tank has a 2.5 inch drain and the manufacturer stressed how quite their return system is when I purchased the system. You have to practically stick your head in the sump to hear any water noise at all. It’s quitter then a mouse walking across glass. I do have a 20 gallon quarantine tank that I specifically purchased because it makes that running water sound, the wife and I really enjoy the sound. Your probably right!! were a little strange that way.

    I also don’t use filter socks because the tanks drain goes all the way into the sump tank and below the water line about 3-inches there is a carbon filter that goes around the drain pipe and seals around the tanks drain area as well to filter large particles. I have to clean the filter about every 2 to 3 weeks just a quick rinse and its ready again. I’ve been using them now for 3 years on this tank, I suppose I should replace them, there only a couple of dollars each.

  • Jules says:

    This is all good but I found that the double overflow pipe is by far the best and simplest to set up.

  • Ted…I don’t think the Bean Animal or Herbie overflow are bad, I just don’t see the benefit for the added complexity and potential leak points. If you want more insurance against a clogged overflow, then two durso drains will do the job. I’ve never had a clogged overflow issue on any of my tanks or my client tanks.

  • Mary says:

    Hey Mark. So what would you say is an acceptable low flow rate turnover? Worried I’m not going to get enough filtration.

  • Dan says:

    Mark, pardon my ignorance but I have a mixed reef 55 with a fluval 306 and I’m kinda sorry for that…the fluval I mean. Plan on another tank, haven’t made up my mind yet on size due to being on the 3rd floor…weight, parallel to tank 16″ center-center joists(rough cut though). I see this thread is referencing overflow boxes, now I was thinking more about, if its gonna be drilled, 2 or 3 holes back wall piped to sump, as in 1/2 drains and 1 return…like the ones I see in some LFS’s. What are your thoughts on the possibilities?!?

  • Mr. Saltwater,

    Nobody said that that a “durso” can’t be quiet. Given a narrow set of parameters, they certainly can be quiet.

    From the perspective of noise and safety and stability, a “durso” or other partial siphon setup has a very limited operating bandwidth. PERIOD.

    In the same context (noise, safety, stability) my overflow system is rock stable, extremely safe and dead silent over a huge range of flow rates from a few hundred GPH to many thousands of GPH, all with the SAME configuration.

    “Terrible Advice” – I have read two of these “Terrible Advice” columns so far (Dursos, and Salt Concentration) and have found both to be rather suspect at best.

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