Herbie Overflow Method Reef Tank Plumbing Guide

Herbie Overflow Diagram


The method was popularized by a Reefcentral.com thread started by a forum member “Herbie” around 2004. As people started using the method on their tanks, many forum threads started and there are literally hundreds of posts out there about it. The difficulty lies not in the method itself, but in sifting through all those bits and pieces of info just to figure it out.

About this guide and a heads up

This guide explains the regular operation, each component of the design, and gives tips along the way. For the sake of simplicity, all of the content and diagrams describe the most simple and conventional Herbie setup, — an overflow box with standpipes coming in through the bottom. In some cases the pipes will have to pass through the side of the tank, but the mechanics of everything will be the same.

You should be aware that:

  • It is not completely a “set-it-and-forget-it” method… It needs to be regularly inspected and properly maintained. See Best Practices
  • There are all kinds of people out there who run the system in one form or another, and they all have a slightly different opinion on how they think things should be done. I am only one of these people. the most important thing is to understand your own setup. You can choose to do things differently with certain parts of the design, but try to be aware of any risks you may be opening yourself up to when you do so.
  • There is another similar method called the “Beananimal” drain (also named after its creator) which is slightly more complicated in design and uses 3 standpipes vs. only 2. The Beananimal is superior in many ways including running a “dry emergency” drain (increased safety), and having much more capacity than the Herbie design.
  • For the sake of clarity, I won’t attempt to explain the Herbie and BeanAnimal designs at the same time. The goal is that you will not only understand the Herbie design after reading this, but start to see it’s limitations.

The Siphon that makes the Herbie work

Any time you have air and water flowing through the same drain, you’ll get noise with even low amounts of flow. This is the main shortfall of single-pipe-drain methods like the Durso and it’s siblings. Aside from running silently, a siphon drain has much more flow capacity because air never runs through the pipes once it gets going.

The way the siphon on the Herbie is achieved is by manually constricting flow on the main drain with a finely-adjustable valve. Once the air is purged from the line and the siphon is fully engaged, it continues to run this way 24 hours per day until something interrupts flow like the return pump being shut off.

The rate that a siphon moves water is similar to a return system. For a return pump, the greater the distance the pump has to push water up to the tank against gravity, the less flow exits the return outlet.

So for a siphon, gravity pulls water faster the higher you go. Vertical distance between the inlet pipe in the overflow and the outlet in the sump helps move more water.

Ideally the pipe should run straight down to the sump, with no horizontal runs. This isn’t always possible, but you should keep it in mind. Try to reduce horizontal runs or use flexible pipe to make curves more gradual.

Adjustment of the Valve

valve aquarium

To begin, the valve is opened all the way — then slowly closed off until the siphon is achieved. Fine adjustments are then made until the flow of the siphon closely matches the amount of water being returned to the tank, which will stabilize the water level in the overflow.

Perfectly balancing the water level until it remains totally still inside the overflow is difficult and time-consuming to achieve even with a Gate valve. Although it can appear stable and stay that way for a while, slight variations in the system such as changes in resistance of water through the plumbing will inherently change the rate of flow over hours or days. For example, the growth of slime in the pipes.


Simply by allowing a very slight trickle of water to enter through the emergency standpipe at all times, you sidestep the nearly impossible requirement of perfectly adjusting the valve. We are talking a trickle here — just enough to negate the need for constant fiddling, but still allowing the emergency drain ample capacity if needed.

To accomplish this, you simply stabilize the water level as best you can inside the overflow, then close off the valve’s flow a very tiny amount past that point. After this tiny adjustment, the water level inside the overflow will rise, very slowly, and come to rest at the level of the emergency standpipe — where the trickle of water will begin seeping down it.

So what is a Trickle?

Using a term like “trickle” leaves the actual amount to interpretation.

If you fill a styrofoam cup with water then poke a hole in it with the lead of a pencil, you will get an idea of what to aim for (and allow) with your trickle. Think “seeping” and not “flowing”.

The Effects of running a Trickle

A slight trickle of water flowing down the emergency pipe has a few effects on the system including:

  • Inside the overflow box, the operating water level remains up at the top. Water passing over the the weir falls only a short distance, so it won’t splash and create noise.
  • A trickle of water breaks the surface of water inside the overflow, preventing any scum from accumulating.
  • The need for constant adjustments is reduced considerably. Sounds great, right?
  • But don’t forget – Your Emergency line goes from dry to wet. Running any amount of flow down the emergency adds risk to the system. It’s a level of risk that many choose to live with and minimize the best they can, but present nonetheless.


Let’s Pause Here… For the sake of discussion, I’ll mention a debate that currently takes place. It regards running an Emergency drain with the Trickle method. There are some people who think that running a strictly Dry Emergency that never touches water is the only way it should be done.

I have the opinion that running a Trickle down the Emergency drain can be done in a safe manner in conjunction with following best practices like using a strainer on the siphon inlet, overflow teeth on the weir and a covered overflow box. I wanted this guide to be just about explaining the basics vs. debating different opinions, so that subject is in a separate post here Herbie Overflow Dry Emergency vs. Running a Trickle

Moving on…

System Design

External Overflow with Herbie Setup


Valve Selection

Due to the need for fine levels of adjustment, installing a quality valve is suggested.

Gate Valve

This valve allows precise adjustments to be made with a minimum effort. The “Spears” gate valve (shown) can be taken apart and is regarded as the best available option.

Gate Valve Herbie

Spears Gate Valve


Ball Valve

The higher quality ones have a smooth opening/closing action, and built in unions which are an advantage. A “Single Union Ball Valve” or “True Union Ball Valve” are the only ones that should be used. They are cheaper and easier to find than gate valves. The common “Straight Ball Valve” should be avoided.

True Union Ball Valve Herbie

True Union Ball Valve

Think Ahead – Add A Union

If the valve doesn’t have a union built in — one should be installed between the valve and the bulkhead so you can easily detach your hoses and get to the valve assembly with relative ease.

pvc union


Main Siphon Standpipe Height

Herbie Overflow drain heights

A sufficient volume of water above the siphon inlet prevents air sucking down from the surface into the pipe, sometimes referred to as a Vortex. If one forms, it creates a slurping noise. They will also interfere with the line going into full-siphon.

6″ is a general rule based on 1″ pipe — it can vary depending on the diameter of pipe of the siphon inlet. A wider siphon inlet is less susceptible to the vortex-effect than a narrow one with the same flow rate. The height of the siphon inlet in the overflow is something you may want to experiment with in your own tank while in the testing phase.

If you forgo the raised main standpipe (such as on the right of pic above) it will take the guess work out of it, just be warned that ALL the water in the overflow will drain into the sump when you shut off your return pump. This water needs to have a place to go without overflowing the sump. Also – any livestock in there (even if they shouldn’t be) will be left high & dry.


Emergency Drain Setup

This drain is what makes the system fail-safe in the event of the main valve standpipe getting clogged. It should be designed simply as a straight (as possible) unrestricted pipe going down into the sump and into the water, never joined with other pipes.

An open-ended standpipe will act as an alarm in a way. With only a small trickle of water seeping into it, it will make no noise. If there is a partial blockage of the siphon line, then the Emergency drain will start to take on more water and you will hear a loud hollow noise, alerting you that it needs attention. This is one reason that you should not try to muffle the Emergency drain.

You want the emergency to have max capacity, so most people leave it open and don’t use a strainer on this pipe.

Don’t install a valve on the emergency pipe — just don’t…no good can come of it.

Emergency Drain Standpipe Height
herbie drain emergency height

As a measure to prevent noise from falling water in the overflow, the emergency standpipe inlet should only be around 1/2″ – 1″ below the height of the overflow weir.

You want the height of the E-drain inlet to minimize water’s falling distance over the weir… but just high enough to limit splashing, no more.

The distance between the E-drain inlet and the top edge of the tank needs to be a few inches to aid with capacity. This is needed in the event of a main siphon line blockage.

If this happens, the E-drain will possibly need to go full-siphon as well. If the standpipe places the inlet too high up, a siphon may not be able to engage on the E-drain if it has to before the tank’s water level swells to the top edge of the tank and starts to overflow it.

Starting and Stopping

When the return pump switches on, and water starts passing through the overflow, the siphon should engage and go back to normal operation completely on it’s own. While this is happening, you may observe a temporary increase in water going down the emergency standpipe. This should only go on for a minute or so until all the air inside the main siphon line can purge through the outlet down in the sump. The siphon will then engage and take on the full capacity you adjusted it for.

Under the tank

Drain line Outlets in the Sump Below

Both drain outlets should run down from the overflow into the sump below. The siphon drain must have it’s outlet submerged, but by <1". Any deeper, and air can't purge from the outlet as easily when the siphon is starting. It should also be located in a sump chamber with a constant water level.

The emergency line is usually also submerged to limit any sound from splashing from running a trickle. This outlet should also be submerged to a depth of by 1″ or less. If the main valve siphon gets blocked, the emergency pipe will take on the extra water. If the e-drain needs to go full-siphon, you don’t want to impede that by submerging the outlet down too far because that is where air is purged.

In the diagram, the emergency drain is shown right alongside the siphon drain. The e-drain does not need to go into a particular sump chamber. It should be plumbed the way that provides the straightest path down to the sump without horizontal runs.

Sump Capacity

When the return pump is shut off, the water level inside the overflow will drain and come to rest at the level of the siphon inlet. The height difference between the emergency inlet and the siphon inlet will determine how much water will drain to the sump. Make sure the sump can accommodate the extra water without overfilling.

More in-depth info about sumps and what to keep in mind with a siphon-based overflow method on this page: Reef Tank Sump Design


Avoiding Common Pitfalls

Trying to Tee the drain line

It is also important to note that you should not attempt to Tee off either drain, as it will most likely interfere with the siphon operation, capacity of the emergency drain or cause other problems.

Horizontal Runs of Pipe

Both the emergency drain and the main siphon drain should be run straight as reasonably possible downwards into the sump, as any horizontal runs will make it more difficult for all the air inside the line to exit the pipe down in the sump quickly. Avoid using 90° fittings and instead replace them with 45°’s or use bendable Flex PVC.


Best Practices for a Problem-Free Overflow Box

Doing these things will make the main siphon less likely to clog.

Use a Strainer

Install a Strainer on the Main Valve Standpipe. This will keep any debris, small snails or algae clumps from interfering with the valve and choking off the drain. There are different strainers out there, and one with smaller holes will protect better, but clog with junk faster. Try to get in the habit of inspecting the strainer when you observe and check on your tank. After all, you want it to prevent clogs, not be the source of one.

You might be thinking, “I don’t need no stupid strainer” — YES YOU DO!

Listen up.

With the nature of a siphon, water moves very quickly through the valve opening. Most times you’ll find that the valve needs to be closed-off in excess of 50% shut to achieve balance from the return. A mostly closed-off valve opening is very small during operation. This makes it more susceptible to obstruction by an object.

Having a strainer in place is the last line of defense before your main drain clogs.

Cover Your Overflow Box

A covered overflow will prevent livestock in the tank from jumping or crawling inside. This is a good idea to further protect the valve against clogs, and can also help to limit algae growth. You’ll also save yourself having to catch a stray fish inside the overflow which is a real pain. A simple piece of acrylic cut to size does the job.

Visual Inspection of the System

You might want to place your overflow in such a way that you can easily look into the box. You want to know:

  1. Is the water level where it should be?
  2. What is the condition of the strainer? Does it need cleaned?
  3. Is there any debris or livestock in the box?

Other Considerations in your System

Is my tank the right size for this method?

Drilling and mounting bulkheads to a tank adds lateral weight and forces on the glass. This limits what size aquariums are suitable for the method. Glass with thickness of at least ¼” can withstand these forces, and generally found on tanks 40 gallons and up.

Don’t waste your time or risk having a future catastrophe later on by drilling a tank that is too small for the method. As always, check to make sure the glass you are drilling is not tempered. There are many videos on drilling glass on YouTube and it’s easy to do with diamond hole saw bit.

Size of plumbing

There is a general consensus that the Herbie method should never use less than 1″ pipe for plumbing, no matter what size tank. You want to be 100% sure that your single emergency drain is completely capable of handling all the flow that the return pump can throw at it in the unlikely event of total clogging of the main drain.

If your tank came pre-drilled with 2 holes in the overflow as in a lot of older “reef-ready” tanks, use the one with a larger diameter (usually 1″) for your emergency and the smaller diameter one for the main siphon drain. Keep in mind that your flow will be drastically reduced on smaller size pipe.

For systems where return pump flow is up to around 330** gallons an hour, running a 1″ emergency line will be sufficient. For tanks above about 90 gallons you may want to bump-up your plumbing size to 1.5” or 2” in diameter. These can handle way more flow.

The trend in the last few years is to use efficient powerheads to create high flow in the tank, while running a moderate amount of flow through the sump. This means you can run a smaller, quieter return pump and not push the capabilities of your overflow design as much which is a smart strategy.

Return pump plumbing

The return pump also plays a part in the operation of the overflow and in short, simple is better. Any variations you add into the plumbing of the return line can have effects down the line.

To avoid having to constantly readjust the siphon valve, the return rate should be kept at a consistent rate. Any fluctuations that would take place from day-to-day should be minimized.

A common practice is to to Tee off the line above the pump to feed a Refugium sump chamber, and this is generally okay to do.

If you are going to Tee the return line, the offshoot should only direct to a place providing consistent resistance.

Some people will add a manifold of valves to direct flow to media reactors. This can be less than ideal with a siphon-based overflow method.

If the return pump is Tee’d off and also feeding a media reactor in the sump, then variations in water flow will start to happen. Water resistance inside the reactor will slowly change as the media becomes depleted or dirty. This in turn changes the rate of flow pushed up to the display, and at the overflow as well.

More in depth info about plumbing return lines in this article here: Reef Aquarium Return Line Plumbing – A How-to Guide

Assembly and Gluing

Your plumbing fittings inside the overflow can generally be fit & threaded together and don’t need to be glued as there is no risk of leaking. This will also allow you to make changes as you initially test out the system by trying various pipe lengths. On the exterior of the tank, fittings and pipe should absolutely be glued with PVC glue (available at any hardware store). Installing unions between the outside of the bulkheads and the plumbing lines/valve is a good idea and allows for the hoses to be removed for cleaning or if you have to move the tank.

More info about how to glue and connect the various pieces: Plumbing Assembly for your Reef tank

Testing the system

There are a few initial tests you should do with the system to ensure problem free operation for years to come. Any problems are better to find out in the garage than in the living room. As long as it passes these tests, then you are ready to go.

  • Close off the siphon valve completely in order to test your emergency drain’s capacity. You must confirm it can handle what your return pump is pumping up to the tank with ease. If using a controllable DC pump, make sure the drain can handle flow at 100 percent power.
  • Ensure you have the right sump capacity by turning off the return pump, then watch both the drain and return lines empty into the sump. Make sure it can handle the extra water (also watch your skimmer).

What about Freshwater?

There is no reason why this method can’t also work for Freshwater tanks. One thing to note – if you have Freshwater plants, there will be a lot of dead pieces/clippings constantly getting into the overflow system. These can clog overflow teeth, or a strainer. Use care.

One Final Note

Ultimately you are responsible for your own tank and your own property — there is the potential for water damage that comes from owning any aquarium. As I have said earlier, the most important thing is to understand how your own system is set up. Learn as much as you can and don’t cut corners. Enjoy your quiet tank!

About this Page

While my original post was written in June 2012, it has grown into a full guide. I have made several edits to clarify some of the concepts and added a few sections based on some if the comments left below and various forum threads linking here. Thanks to those who have participated in the discussion. Ask me a Question using the Contact Form or write it in the comments below.

  • Not_Bob

    Thanks for this site. The one question I have after reading any sites about the Herbie overflow relates to the emergency drain. Most sites show the emergengy drain as being an inverted U and say to run the drain below the water surface of the sump. Will that work if there is no air hole in the U?

    • http://gmacreef.com gmacreef

      I have seen the added elbows to form the downward U on the emergency drain on a few diagrams and pictures such as you described. From what I can gather it is a modification that is done to minimize noise. There can sometimes be a hollow sound echoing through the emergency drain – however in my experience this just means that the valve on the main drain isn’t adjusted correctly (too little flow) and is allowing too much water to pass through the emergency drain. It is normal for this to happen as the siphon gets going again (such as after you turn your return pump back on) You want just a trickle of water going though it which won’t make any noise. I don’t see a need for it, and it has the potential of being something that a snail could climb into and you wouldn’t notice it. I can’t speak to experience to whether you would need an air hole in the “U” — I just wouldn’t use it at all.

      • Not_Bob

        I think I’m with you and would not use the inverted U; however, I still can’t see it working with the sump end submerged, too. Thanks for getting back to me.

        By the way, I hope to try a Herbie overflow in a couple of weeks. I’m looking forward to it.

  • http://leapfrogthis.blogspot.com Shane Hopkins

    I assume this system would make the BeanAnimal Overflow System Obsolete due to the fact that this system is MUCH less complex. Anyone have experience with both or know of any features in the BA system that the Herbie does not cover? The Bean Animal Silent Overflow can be seen at Reefcentral dot com in the DIY forums. Thank you GMAC for posting this simple system with thorough explanation. I will be incorporating it into my current reef build. Cheers!

    • http://gmacreef.com gmacreef

      I am not sure that the Beananimal system would be made obsolete, as it does have the advantage in that it deliberately prevents a siphon, meaning that it can go into full operation in seconds while the Herbie takes longer (usually under a minute) for air to be purged from the system and go back to silent operation. I have seen a few demonstrations on YouTube of the Beananimal, but nothing to convince me that it’s vastly superior. The main advantage I see with the Herbie is that it uses only commonly available parts, way less fittings and is just plain simple. Most people don’t want to spend hours rounding up parts, researching, and then assembling an overflow. Although there is a decent writeup of the system basics on the beananimal website, people who have questions have to go to the massively bloated Reefcentral thread to get their questions answered. I also think personally that the idea behind using the beananimal awards a lot of supposed benefits to using a long Calfo-style overflow which is in many cases overkill.
      Here is a link to the guide.
      Bean Animal Overflow System

  • Azeem Khan

    Is an internal overflow box absolutely necessary?

    • gmacreef

      Well that depends. The siphon and the emergency line will operate the same whether or not they are contained in an overflow box. Overflow boxes provide a few benefits: they allow you to keep the water in the tank at a set level, hide ugly PVC pipes, and provide more protection against debris for the main siphon drain (which should have a strainer on it).
      If you are not running an overflow box at all then there will be a large volume of water that will fluctuate between the tank and sump during the stop/start of the Herbie operation that you probably don’t want. The best looking way to do it in my opinion is to run an overflow box that is mounted to the back of the tank for your standpipes, with a channel for your overflow cut through the glass. See the pic in the post.

    • gmacreef

      Well that depends… The siphon and the emergency line will operate the same whether or not they are contained in an overflow box. Overflow boxes provide a few benefits: they allow you to keep the water in the tank at a set level, hide ugly PVC pipes, and provide more protection against debris for the main siphon drain (which should have a strainer on it).

      If you are not running an overflow box at all then there will be a large volume of water that will fluctuate between the tank and sump during the stop/start of the Herbie operation that you probably don’t want. The best looking way to do it in my opinion is to run an overflow box that is mounted to the back of the tank for your standpipes, with a channel for your overflow cut through the glass. See the pic in the post.

  • Kevin M

    My herbie overflow has to be “restarted” every time the return pump is turned off. The last pipe from in intake goes fully into the water in my sump and if i turn it off and back on again, I have to take the last pipe off and let it drain for a while before I put the pipe back on or else it will just go through the emergency drain and not use the actual drain pipe.

    • http://gmacreef.com/ gmacreef

      If your main drain siphon is not restarting on it’s own in under a minute it then it could be a couple things. This can usually be corrected by shortening the standpipe height in relation to the emergency drain. There has to be a sufficient amount of water to create enough pressure in the main drain to purge the air inside and restart the siphon. This can also be helped by making sure the drain line exits into the water level in the sump by only a few inches so the air in the line can escape easier.

  • George Ziras

    I want to thank you for your very informative article about Herbie overflow.

    Recently I design my own in a 75g tank. I have the e-shopps nano overflow and the eheim 1000 pump as return.

    I’m facing the following issue with my herbie. When I’m closing the ball valve to reach the point where my emergency hole is, automatically the water level in my display is rising as the water in the overflow box behind my tank rises. This is normal? Also it seems that I can’t adjust the water level in my display tank by lowering the overflow box, maybe there is a relationship with the return and siphon?

    Best Regards

    Ziras George – Greece, Athens

    • http://gmacreef.com/ gmacreef

      Thanks for your comment, but I really can’t give you any advice on this, as I have no experience with any type of hang on overflow box. The design of them is just too flawed IMO, and to be honest I am not sure how anyone can trust that these devices will restart a siphon before the tank overflows. To be blunt – I think that they are garbage… yet also unfortunately too commonly seen in this hobby. Drilling the tank is the only way to go and much easier to do than one might think.

  • Brian Fischer

    What is the advantage of placing the valve near the overflow rather than at the sump? Wouldn’t the pipe fill faster with the valve installed near the sump?

    • http://gmacreef.com/ gmacreef

      I don’t think the exact position of where the valve is installed on the siphon line makes any discernible difference at all as far as the mechanics of the siphon are concerned. It is more a matter of convenience and having easy access to reach the valve with your hand to make those fine adjustments. The advantage to mounting it high in my case is it’s a lot easier to dial in the flow when you have your hand on the valve and a sight-line of the water level in the overflow. If the valve is mounted under the cabinet, then that makes it a bit harder because you’ll have to go back and forth. On my tank I opted to install it under the overflow so I could reach it while standing next to the tank.

  • Boyu Chen


    Great website, much better illustrated and explain! Better than BA website….BA website got just too much redundant words too little important details…..

    But i got a real worrying question regarding Herbies, you said, You should be aware that: It is not completely a “set-it-and-forget-it” method… It needs to be regularly inspected and properly maintained.

    What should i inspect and maintain? I am not following on that!

    One more to go… On the BA web he said his is absolutely “set and forget” type….. But i don’t understand the very basic of his system about two hose face down, that makes me worried when pump tuen off, and the drain wont start….. Do you know how BA start it self?

    • http://gmacreef.com/ gmacreef

      The statement “It is not completely a ‘set-it-and-forget-it’ method… It needs to be regularly inspected and properly maintained” is just me beating the drum that you should use a strainer on the main siphon drain, and it is something you need to be keeping your eye on. Depending on what type you use, it will eventually become dirty. Cleaning isn’t normally necessary too often, but is critical for problem-free operation. The use of a strainer is really the only way to claim that the method is completely safe in my opinion. Doing this will ensure that the Main siphon drain is protected — as a clog is most likely to first occur at the narrow choke-point of the valve. I added a link to the strainer section at that part of the guide to clarify.

      The topic of choosing a Herbie design vs. Beananimal design is really a subjective matter of personal taste and what level of extra safety/redundancy you desire on your own tank versus how much time and effort you want to spend researching and building an overflow.

      I’d rather not discuss specific questions about the bean design here as it is out of the scope of this post, but may cover the method in another post in the future. Thanks for commenting.

      • Boyu Chen

        Thank you for replying, I rather say the Heribie is easier to understand, the strainer, ball valve, they are easy to understand why there are there, to my knowledge, understanding your design, is it actually the way I would do if I have not yet seeing yours.

        I know the difference between bean and heribie, the bean is just one pipe more. I am not going too anal with the topic, it is not the next UFC fight, the main question here is, how well the silence and “set i and forget it” the herbie will go? I know you said watch out for clog on the pipe, i think people with a tank will always go tinkle with them….so no problem there, I am all freshwater, no marine water, no sea monster thanks… so if the pipe is check every day, (i mean we all go watch our tank daily right? haha that is the reason for it…) Can I say the herbie is “set it and forget it” design? I really really want it to be said from your mouth…!!! because I don’t want to waste money and make something not gonna work well, but again, I never build a overflow before, this is my first round, so I would very love to see a knock out!!!!! can you please let me know it is “set it and forget it” like I assume it to be?

        Last question, what fitting would you use on the drill bottom tank?

        So many questions, sorry about that, I really love your simple design, and it will be my way to do it too.

        BTW, my tank size is 100cm L x 50cm D x 50cm H about 240L.

        Best regards

  • glen segarra

    Thanks for taking the time to put all this up in a way that is easy to understand. You’ve saved me hours!!!

    Is there any reason not to make the emergency overflow a slightly larger diameter than the main drain?

    • http://gmacreef.com/ gmacreef

      Glad it helped you!

      You can make the emergency drain larger in diameter, but it’s not an option for everyone who is just retrofitting an existing tank with the method. If you have 2 pre-drilled holes, then yes — the larger one should be run as the E-drain to get max capacity out of it.

  • JaCoBz2007

    Hi, where can I purchase these strainers or is there another word for them as I can’t find them anywhere.

    • http://gmacreef.com/ gmacreef

      They are called Bulkhead Overflow Strainers and you can get them from Bulkreefsupply. Some people also create them DIY with a tube made out of plastic mesh.

  • Chris Swanson

    You rock! I started with a durso drain and the bubble draw was not acceptable. I had already drilled the tank and only read most of this article when I thought: a tee! Then I saw Boromir. I laughed with that all day. I drilled a third hole in my living room and now have a Herbie and no bubbles. Thanks!

  • mick

    Does anybody know of anywhere in the UK that you can buy these strainers from because I can’t seem to find them anywhere?

    • http://gmacreef.com/ gmacreef

      These are also a fairly easy to make DIY item by making a tube out of sturdy plastic mesh or “gutter guard” material.

  • Jim Rogers

    Thanks for the site. I’m completely new to this hobby (haven’t even gotten my tank yet). I may be purchasing a 90 Gallon tank that I plan to drill. Do you have pictures of where the drill holes should be or how an overflow box is placed in the tank. For that matter, where and what overflow box to buy? I can’t see any of that in the pictures. It looks like the overflow is outside the tank. I’m completely confused. Details please? Thanks

    • http://gmacreef.com/ gmacreef

      Drilling the tank requires some research of where to put the holes in proximity of the edge of the glass. I may expand the site’s content to cover some of that info in the future.
      Internal Overflow boxes are the most common choice if you are installing on a standard tank. They are generally made of 2-3 custom cut pieces of glass that are sized to the tank, and siliconed in place. The picture you speak of is my custom built tank with an external overflow.

  • lippington

    Is it possible to send your return flow back up the inside of the Emergency overflow pipe rather than having it run externally please ?

    • http://gmacreef.com/ gmacreef

      In almost all cases I would say no. Maybe if you had a very large 2″ emergency you could pass a small pipe (say 1/2″) through it and have enough capacity to do it safely. You would also have to factor in the increased friction losses from having another pipe in the line. It would of course depend on the return rate from the pump. I would advise against it because it would complicate the emergency going into full-siphon. It would be very susceptible to clogging compared to an open pipe, which is what the emergency line should be.

  • https://plus.google.com/u/0/+WilsonWong57 Wilson Wong

    Great Post! THANKS LOTS!


    Thank you for the clear and concise diagrams. My question is why do you want the emergency drain below the water level in the sump? It would be safer to have it above the high water mark to ensure it flows without resistance should it be needed. If you had an issue with the water level in your sump and the e-drain ends up 5″ below the surface it may have a problem starting. The main siphon line is submerged only to prevent noise, otherwise a full siphon can happen with a wide open bottom. The water only creates back pressure, yes?

    • http://gmacreef.com/ gmacreef

      Well ideally the siphon outlet should be in the 1st sump chamber that has a consistent water level. This will have all the water passing over a baffle into the next chamber. This eliminates the possibility of the 1st chamber overfilling. Most overfilling is caused from back-siphoning from the return line and drainage from the overflow box. This happens when the return pump is turned off, not during normal operation.

      The siphon line being submerged allows air to exit but not re-enter. It is critical to the design. The length of pipe below the valve needs to have the air purged before a siphon will start, otherwise it just acts as a gravity drain.

      Some people have the e-drain outlet higher than the water, so that when the e-drain is engaged, it will create enough noise to alert them with the splashing etc. If you are running a trickle through the e-drain then it will be loud during normal operation.

      I think it is better to run an emergency submerged 1″ in a constant-height sump chamber in the same way as the main siphon. This is because if the main siphon has a total blockage, then the emergency could also go full siphon if needed. The E-drain will still create a loud hollow sound if the flow reaches levels higher than just a trickle.

      Good question – thanks for commenting.

  • Alberto De Armas

    Help please. Building a 330 gallon tank. Center back overflow. Want to drill 4 holes. 2 for a 1″ return each and the other two to build the Herbie overflow. My question is what size hole would you recomend to be able to handle a return pump of about 2500-3100 GPH? Would a 1.5 siphon stand pipe work with a 2″ emergency? Thanks.

    • http://gmacreef.com/ gmacreef

      If you are building your own overflow and are not limited by size constraints I would recommend adding a third drain pipe (dry emergency) to the drain setup. This will make it a Bean overflow. Using a 2″ bulkhead for the E-drain will mean that you have to build a large overflow box to accommodate it, and adding a 3rd pipe is a better use of the space . 1500GPH is about the limit of 1″ pipe at full siphon so I would use 1.5″ for all three drain lines. I also would recommend only running 5-7x of display volume for return rate.

      • Alberto De Armas

        Excellent advice. One last question if I may. Would you rather do a coast to coast overflow or a conventional overflow? Whichone would you go with if it was your tank?

        • http://gmacreef.com/ gmacreef

          I can see the value in having a coast-to-coast overflow for the benefits of surface skimming and gas exchange. Unfortunately most of the DIY builds of a C2C I’ve seen are awful to look at in a tank and detract from it’s appearance. I don’t think I would ever put an internal “L” shaped C2C box in my own tank for this reason. It seems like the better an overflow design is in terms of functionality the worse it tends to look!

          I am working on a new post about some of this stuff. It will cover things like the types and sizes of overflow teeth and why you need surface skimming in the first place. I hope to cover the design / aesthetic appearance aspects of overflows as well.