Durso Standpipe Overflow Drain (How It Works, DIY Plumbing, Silencing)

Image Credit: Paul Thompson via Flickr
Image Credit: Paul Thompson via Flickr

Durso Standpipe Overflow Drain (How It Works, DIY Plumbing, Silencing)


If you have an aquarium, you’ll need a plumbing solution and the Durso method is one of the most simplistic and space-saving options available. In this article, we will discuss its benefits and how you can make your very own standpipe.

What is a Durso standpipe?

Durso standpipes are one of the most simple and reserved designs for aquarium plumbing. It was designed by Richard Durso, hence the name, and uses a single standpipe with an elbow pipe sticking out neat the top of the waterline. The design of the Durso helps to reduce the noise of water flowing to your sump and is much easier to install than other plumbing methods. Due to how little space it takes up, the Durso standpipe is a widely used method with smaller aquariums. It also features an end cap that acts as a way to control the flow of air within the pipe. The benefit of this to create a siphon for the standpipe to better flow the water through the drain bulkhead.

Aquarium Overflow Types

Durso overflow parts

To properly install your Durso standpipe, you are going to need a few things. Here is a list of the preferred materials to make this overflow method work for you.

  • 1 1/4 inches PVC end cap (vent hole)
  • 1 1/4 inches connector PVC
  • 1 1/4 inches PVC street-ell
  • 1 1/4 inches PVC tee
  • 1 1/4 inches PVC pipe (this pipe should be as long as you need to reach the height of the water level with tee attached. About half the tee will be submerged when it is all said and done) Measure your tank.
  • 1 1/4 inches PVC coupling
  • 1 – 1 1/4 inches reducer bushing
  • 1-inch connector PVC
  • 1 inch PVC male adaptor
  • bulkhead
  • Teflon tape
  • Glue
  • Silicone
  • Masking tape
  • Overflow box
  • Hole saw bit
  • Drill guide (preferable)

Durso Overflow DIY

Here is a guide on how to assemble the Durso standpipe in your aquarium. Please make sure you have all the materials listed above before you start so this is a streamlined process from beginning to end. There are two common kinds of overflow boxes but for this guide, we will be using an external method. The basic premise remains the same for an internal overflow system but you will need to make adjustments to where you drill the hole and your piping might need to be moved around a little bit.

  1. Drill a hole into the side of your aquarium. To make things simplistic, it is always a good idea to place your sump directly under your Durso standpipe plumbing or as close as you can get it. The standpipe is reliant on gravity so horizontal piping isn’t ideal.
  2. You should outline where you would like to make the hole. For an external overflow box, it should be about where the water level crests in your tank as this bulkhead will be used to let water into your overflow box from your display tank. To make the hole in your tank, place your tank in an area you are okay with getting wet. Alternatively, you can create a dam with plumber’s putty. You will be spraying water over where you would like to cut the hole in your aquarium to keep the drill bit cool. make sure to place towels down around the area you will be working. The idea is not that the towels will soak up the water but that they will help catch glass as it falls. For extra protection, consider using masking tape under the outline of the hole to catch more glass and the final disc. Wear PPE for your hands and eyes, while you cut a 1-inch hole into the desired spot on the aquarium.
  3. Once you have drilled your hole, attach your overflow box to the side of your tank with silicone. The sides of the overflow chamber that are coming into direct contact should be the only parts being lined with silicone. Press it down against the tank and wipe the sides to ensure a complete seal.
  4. Install your bulkheads into the drilled hole in the aquarium and the bottom of the external overflow chamber. One bulkhead will be used to let the water into the overflow chamber. Note, that it might be prudent to install a screen into your bulkhead to prevent any adventurous fish from falling in your overflow. Just because your bulkhead is located at the height of the water level doesn’t mean they can’t be sucked in.
  5. Time to assemble the Durso standpipe. Unless otherwise instructed, use the Teflon tape to help secure the pipe. Install the 1 inch PVC male adaptor to the bulkhead at the bottom of your overflow system. Next, attach the 1-inch connector of PVC to the male adaptor.
  6. Working our way up the standpipe, it is time to connect the 1-inch reducer bushing. Grab the 1 1/4 inch PVC coupling and attach it to the reducer bushing. Make sure to glue both of these pieces securely into place.
  7. Attach the large 1 1/4 inch PVC pipe into the coupling. This piece should be long enough that it can get the end cap to be about at the same level as the top of the aquarium.
  8. Grab your 1 1/4 PVC tee and attach it to the PVC pipe but make sure not to glue this portion. only use Teflon tape. Connect the 1 1/4 PVC street-ell (the elbow piece) into the horizontal part of the PVC tee.
  9. Next glue the small 1 1/4 PVC connector to the top of the PVC tee. Finally, install the end cap to the vent hole of the connector.
  10. Install the pipe that you need to reach your sump now. The end of the pipe should be submerged into your sump water about an inch.

Adjusting the level in the overflow box

Now you are done, right? Not quite. We need to ensure that this Dusro standpipe will work for our purposes. We will want to adjust the flow rate of the tank’s system to make the most of what is possible with the standpipe. Since we used an external overflow system, we are limited by the hole and strainer that was installed into the side of our display tank. As well as the bulkhead that is attached to the Durso standpipe. These factors will be what limit the flow through your overflow system the most.

The water level in your overflow should be able to sit right at where the top of the PVC elbow. You should be able to see the top sticking out of the water a few centimeters. If you are noticing that water is moving through your system too quickly you might need to just the rate of your return pump. The level in the overflow should remain stable when it is set correctly.

How do you quiet a Durso standpipe?

The first thing your need to consider is where the noise is coming from. If the noise is emanating from your sump, then your drain line pipe is sticking out of the water. If you want it to be silent, make the piping longer so water is deposited quietly.

If you followed the restricting of the pipe’s diameter towards the bulkhead, you shouldn’t;t be hearing a noise from the standpipe itself unless the air hole is clogged somehow. Double-check that air can escape through the air hole. Durso standpipes can run quietly but they need to be designed from the very beginning with that in mind so if you altered the design to fit your own desires, you might need to make some changes to your tank plumbing.

Durso Standpipe intake strainers

With the current design that we built, there is still an issue that might have been bugging you. There is still a giant hole in the Durso standpipe PVC elbow. The opening can let anything that might float in from your aquarium get into the plumbing which could cause a clog down the line. To avoid this, we want to install an intake strainer into the stand pipe.

There are a few methods you can consider for your intake strainer.

  • Foam filter – A foam filter is a cheap and easy DIY option for your stand pipe when you are in a pinch but many aquarists recommend against using it because it will filter plankton out.
  • Perforated pipe – These are the most effective but you will most likely need to buy one from a seller or find one in a kit. You might try to repurpose some extra PVC pipe and have it match the same perforated design as well.

Durso standpipe bubbles?

If you notice that your Durso stand pipe is creating bubbles, the most likely cause is that the end cap is actually stopping the PVC pipe from creating a full siphon. The bubbles can actually be sent through your plumbing and create microbubbles that look annoying in your reef tank. ‘

The best way to deal with this issue is not to deal with it in the overflow chamber but to fight it in the sump. You can install a filter sock onto the drain line right before it enters the sump. The filter sock will help to trap the bubbles before they even enter the sump.

You can also install a refugium into your sump and begin growing macroalgae like sea lettuce to redirect the direction of the bubbles towards the surface of your sump chamber.

Dual Durso Overflow

Some aquarists claim success using not just one Durso standpipe tube but two in the same overflow chamber. Logic would dictate that it should allow for drains that are much more effective but that often isn’t the case. However, remember that part of the issue with flow rates was the size of the bulkhead or teeth spacing that allowed water to enter the overflow chamber. Just because you have more than one standpipe does not equate to double the plumbing in this case.

Durso overflow surging?

A Durso standpipe that is surging is trying to siphon but failing and repeating the cycle over and over again. You can better identify this situation if there is a noise coming from your plumbing that sounds like a toilet flushing. Before you do anything double check your drain lines and the configuration of your standpipe. Remember that a Durso pipe needs gravity to work effectively and if your system is slanted or even horizontal in places, it probably won’t be very quiet. If your tank is still gurgling to being noisy, you should try is to add a little bit of aquarium-safe water to your sump and main tank.

Durso vs Herbie overflow

The Herbie is actually pretty different from using a Durso design. Herbie overflow uses two standpipes: one is set at the middle of the overflow chamber’s water level while the second is an emergency standpipe that is right at where the water level crests in the chamber. The Herbie has a few things going for it. First, it can cut down on noise significantly thanks to the full siphon of the main standpipe and the trickle effect that is created with the emergency drain. Second, it has a second emergency standpipe that will help if the chamber overflows. It also allows the aquarist more control compared to using a Durso standpipe thanks to its gate valve (or ball valve) connected to the main PVC pipe.

The Herbie might be less noisy but it does take up more space in your display tank than the Durso and will require at least one more bulkhead to be installed for the emergency drain. However, in terms of sound quality and emergency preparedness for overflows, it comes out on top.

Final thoughts

The Durso can be a reliable and safe plumbing option but it does have slightly less control than other methods over sound and flow rate. The only control you have for your plumbing in this regard is the rate your return pump affects the water level in your display tank which displaces it into the overflow chamber. However, a DIY project is reasonable and has the potential to be modified in the future.

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