Suitable Pipe Materials for Plumbing Reef Aquariums

Choice of Pipe Material for Aquarium Plumbing

The most common choice for plumbing is PVC – a time-tested material that is both cheap and easy to find at hardware stores in various sizes. It is available in Rigid and Flexible types.

It used to be common to use rigid pipe for a whole system, but many more people nowadays are going with types of Flexible hose for the majority of their plumbing.

Going with PVC and glued fittings generally results in the fewest problems, and this guide outlines some of it’s benefits. Other types of tubing are sometimes used, and they are also discussed.

Where to use Rigid vs. Flexible?

Flexible pipe can be used throughout a system. For places where a straight pipe is required, rigid pipe should be used. For example, on overflow standpipes.


Flexible Tubing Benefits

  • Bendable tubing allows you to gradually curve the pipe, rather than use elbow type fittings, which simplifies the setup. This results in less friction from fittings and greater efficiency.
  • Softer types of tubing transfers less vibration between the pump and the rest of the equipment, resulting in less noise.


Types of Flexible Pipe

Flex PVC (Spa Flex)

Flex PVC has the best fluid dynamics of any other material — Less resistance from fittings and sharp turns in the plumbing creates better flow.

It is glued with the same solvent as regular PVC. While not as easy to bend as some other types of flex tubing, it will never pinch.

It’s flexibility is affected by temperature, becoming easier to work with as it warms up.

Quick Tip – There are a few colors available these days. Whatever you do, don’t spray paint Flex PVC, it will become permanently sticky and you’ll have a real mess on your hands.


Braided Vinyl Tubing

This tubing is identified by a lattice of visible fibers woven inside the sidewalls. This gives it lateral strength and protects against pinching when the pipe is bent. Mostly available in clear types, it can be prone to algae growth.

Vinyl Tubing

Because it can pinch and kink very easily, non-reinforced vinyl tubing should be avoided when plumbing reef tanks. Anything important such as the drain lines or return lines require more strength. Some people use it on small reactors and pumps because it is easy to work with, but there are better alternatives.

Silicone Tubing

While somewhat expensive and less common, tubing made from Silicone is starting to become more available. Silicone is excellent at reducing vibration from the return pump, and a short run of it can be installed from the pump into the main return line.

The Shortfalls of Tubing

  • Possibility of Failure – Tubing differs from PVC in that it is assembled differently. Rather than using glue, barbed fittings use collars that are tightened around the tubing. This can present a few hazards: Collars or “Hose clamps” made of metal can be prone to rust when near damp saltwater (such as inside a sump). Collars or clamps made from any kind of plastic will not rust, but are much weaker than the metal clamps by comparison. This alone makes it less secure than a permanent, glued line in comparison.
  • Pressure Sensitive – If you use a pump to push water through tubing, water pressure is created. If the pressure in the line gets to be too much, such as if a kink forms in the tubing, the line can “blow a fitting” – when the plumbing comes apart. As you can probably imagine this can have potentially disastrous results. Any kind of pressure fit system is more prone to this than a permanently glued line.
  • Barbed Fittings Reduce Flow – Aside from safety, Tubing has a major shortfall compared to PVC. The fittings are inserted into the hose and clamped from the outside. This reduces the inner diameter of the pipe, significantly lowering flow capacity. In places where you want maximum flow capacity, tubing is not a good choice. For example, a drain system.

Running tubing as safely as possible

An example of this would be choosing to have any kind of reactor with barbed fittings running with the whole plumbing loop inside the walls of the sump. If there is a leak, it will be contained this way and will not let water escape the system as the pump continues to run. More info about this practice here: Proactively avoiding a Flood on your Reef tank


What is the difference between Schedule 40 vs. 80 PVC?

Most people use Schedule 40 pipe and fittings, generally white in color, for reef tank use. The difference with schedule 80 is that it has a higher pressure rating and is dark gray. Reef tanks have low pressure compared to a lot of other applications, so there is no advantage to using Schedule 80 on most fittings. Valves that are Sch. 80 are usually of a higher quality and might be worth the extra price. Many people using Sch. 80 fittings do so simply because they prefer the dark gray color they come in. While you can generally mix and match Sch. 40 and Sch. 80 with glued slip connections, you may find that the two have different threads that will not always match up even though they are the same size.

Herbie method for Dual Overflows

Many aquariums with dual overflows can be retrofitted to use a siphon-based Herbie Overflow. This post assumes a bit of understanding of the system so read through that if you’re just starting out. Having more than 2 pipes available allows for a secondary dry emergency line in some configurations. Those may be considered a Bean Overflow by some people.

It has been a common practice in the past for builders of these larger reef tanks to set them up with the “reef ready” design. Inside each overflow are two holes for bulkheads; one for the return, and the other for a single-pipe-drain. Some common brands are Marineland, Perfecto and a few others.

Some universal rules:

  • If you have two pipes in the same overflow with different diameters, then always use the larger one as the emergency drain. You want it to have maximum capacity that matches or exceeds the capacity of the siphon drain.
  • Don’t “Tee” any of the pipes with the Herbie for best results
  • With a long tank that has 2 overflows, it becomes more important to make sure it sits on a level surface so that the overflows take on the same amount of water at each end.

Reasons to Update from a Single Drain System

Single-pipe-drains require no adjustment, but have several drawbacks. Air and water move through the drain at the same time, creating noise. There are many contraptions that attempt to quiet the drain with varying success (Durso, Stockman, Hofer etc.). If air moves down the pipe, there will be splashing down in the sump which can generate microbubbles or lead to salt creep. These drains also have only a fraction of the capacity of a siphon-based drain.

By converting the tank to use a siphon-based method like the Herbie or Bean method, the drains become silent and get more capacity to move a lot of water.

A note about “Reef-Ready” tanks

Reef-ready tanks may have small bulkhead openings compared to the size of the tank. Do your homework with flow rates and required turnover if you have a tank with anything less than 1″ bulkheads in the overflows.

These tanks often come with a return line running up through the overflow box. These are often changed into siphon standpipes with a Herbie conversion because they are often the smaller of the two in diameter.

Option 1: Independent Siphon/Emergency in each overflow

Due to the sheer volume of a tank that has two overflows – It’s often a really good idea to have a 2nd emergency line available.

With this setup, both overflows have both a siphon drain and emergency drain — like you would on a tank with only one overflow.

You may want to adjust one siphon so that it takes on less water, just enough to provide adequate surface skimming. The other siphon can then be used as the main point of adjustment, and can be the one that is easier for you to access.

With the amount of water that an single Herbie can move, having two means the siphon valves will be closed-off a considerable amount. This can mean finer adjustments are necessary.

Having two independent overflows can result in having to do too many fine adjustments which can be tedious. For this reason, some people choose to go a different route.

Option 2: Joining the two overflows so they act as one

If the two overflows can be connected with a “Tunnel” of sorts, then they will act as one overflow with two weirs. This is commonly known as a Balance Pipe. A pipe that spans behind the tank, passing through a bulkhead at the rear of each overflow. It could also be done inside the tank, but wouldn’t look very good unless covered with sand.

You will want the bulkheads for a Balance Pipe lower in the overflow so they are always submerged (below the siphon intake). Larger diameter pipe will allow water to equalize between the two overflows quickly. Strainers on each bulkhead opening will ensure that nothing gets in the pipe.

This setup allows for 2 pipes to be used as a typical siphon / emergency combo. The third pipe is used as the primary emergency and the fourth pipe can be used either as a secondary dry emergency, or as a return output running over the overflow wall into the tank.

Option 3: Only using one overflow and disabling the other one

If the diameter of the drains are of sufficient diameter — only one overflow may be enough.

Your main overflow would operate as a conventional Herbie drain setup with 2 standpipes (siphon and emergency).

In the unused overflow, one pipe is used as a dry secondary emergency, and the other as a return.

This method would makes the 2nd overflow dry. In order to keep it dry, you would have to slightly raise the level of the weir slightly. On this dry overflow water would only enter in the unlikely event that both the main siphon and emergency were completely blocked. If you don’t raise the weir on an unused overflow — it fills with water, and a chamber of nearly stagnant tank water is undesirable.

Option 4: What to Avoid – Teeing both siphon drains together

Some people wish to have only one drain line going to their sump, so they attempt to join the two Herbie siphons together. This is usually done below the tank under the bulkheads by using a “T” fitting.

This setup should be avoided.

You see, it is nearly impossible to keep the water level in two separate overflows balanced if they’re connected by the drain line. A siphon will always function as one unit, so the two intakes will affect each other no matter what. No configuration of valves or having equal lengths of pipe will change this.

The reason is that there are slight variations in flow from each siphon, like algae on the strainer or overflow teeth. These variations will always be present and changing the flow in the pipes over hours or days. One line will always affect the other if they connect in any way.

Gaining control over the water level in each overflow is only possible with individual siphons, or by connecting the two overflows with a Balance Pipe. A siphon must have it’s own independent valve and pipe extending down into the sump water to a chamber with a constant water level.

What about Teeing both Emergency drains together?

Never do that – Anything that lowers capacity of an emergency drain should be avoided at all costs.  Ideally an emergency drain will go full-siphon, and this would be hindered by being Tee’d into another pipe. Siphons also can’t start as easily with with horizontal runs in the drain line.

Plumbing Reef Tank – Cutting and Gluing Pipe, Mounting Bulkheads

Plumbing a reef tank is something that might sound harder than it is. Even if you’ve never done much DIY work before, you can do this.

Here is what to know about how to measure, cut and glue your plumbing. Some basic info about what materials to select is in here as well.

Choice of Piping Material

The most common choice for plumbing is PVC – a time-tested material that is both cheap and easy to find at hardware stores in various sizes.

Info about how to choose pipe material is presented on Suitable Pipe Materials for Plumbing Reef Aquariums

Where to use Rigid vs. Flexible?

For overflow standpipes, rigid tubing should be used. Other than that, flexible tubing can be used throughout. Flex tubing will lessen any horizontal runs, which is beneficial for siphon based overflow methods like the Herbie Overflow.

Cutting PVC

handheld pvc cutter
The easiest way to cut all types of PVC and other tubing is with a ratcheting PVC cutter. This handheld tool is quick and results in nice, square cuts with no dust up to about 1-1/4″ pipe. For larger diameters, wood saws such as a miter saw must be used. A normal wood cutting blade does the job. Be aware of where the blade is oriented and where it will shoot the dust. Be sure to wear eye protection because of the plastic dust or shrapnel. A full-face shield is better.
Care should be taken when cutting pipe with any kind of power tool. Supporting the piece can be a challenge so get a helper to hold as well while you make your cut. Remove any burrs before you glue anything.

Test fitting

Going with “Measure twice, cut once” you should assemble your plumbing before doing any gluing. This will reduce do-overs and trips back to the store. It’s also helpful to mark the orientation of the fittings with a Sharpie so they line up at the proper angle when you glue them. While fittings are supposed to be universal, you will find small differences in pieces from different manufacturers.

Gluing PVC

Gluing should ideally be done in a well-ventilated area over a drop cloth of some kind. The term “Gluing” is used only to describe the process, as you are really using a solvent cement to chemically bond the two pieces of PVC together. The bond that is created is completely permanent, and pieces will have to be cut or sawn apart.

You may want to practice with a few test pieces to get a good connection without using too much Cement. If you use too much primer or cement, it can result in messy drips and runs all over the pipes that can look ugly. Here is a good video on how to make a connection:

Primer is almost always purple in color and should be used to prepare the surfaces that will receive the PVC cement. There are some people that say that using primer isn’t generally needed with brand new pipe, and that it’s made to help out plumbers in a hurry who might not be able to fully clean off a pipe fitting. This may be some truth to this, but using primer will arguably result in the best possible bond.There are areas of the USA that require the use of primer as part of building code for PVC connections. This should give some idea of it’s importance.

For the cement, there are clear types but the most common variety is dark gray in color. An advantage of the dark gray glue solvent is that it makes it easier to visually confirm you’ve applied it to the pieces completely before assembly.

One of the most important things to make sure of is that your PVC primer and solvent is not expired. It should have an expiration date on the can somewhere, often on the underside.

What type of Bulkheads should I use?

bulkhead fitting reefThe Bulkheads I typically use are called “Bulkhead ABS Thread x Slip (Thread on the Flange/Head side)”

These are a good choice for the Herbie System. Threaded fittings (like standpipes) can be installed in the tank to the flange side of the bulkhead, and the outside end glues to a piece of PVC for a secure, permanent connection.

Threaded Fittings

These fittings are self explanatory but there are some things to be aware of. You should not use Teflon tape as it is intended for metal. Using it with PVC will usually result in an inferior seal. Threads can vary by manufacturer and also by Schedule (ex. 40 vs. 80). Threaded fitting like unions generally should be tightened to finger-tight, then 1 to 2 turns more. This can generally be done without any tools. You should not use any kind of glue or paste. The only suitable thing to use on the threads is non-hardening thread sealant. Most people don’t use anything.

Drilling Glass

With the proper bit, this is quite easy to do. Take your time, make sure the bit is lubricated with water, and let the bit do the work, not the pressure of the drill.

After several questions about drilling glass, I decided to expand this info on how to set up and make the holes. Drilling Aquarium Tanks with a Diamond Glass Hole Bit

This video shows the basic process but you really shouldn’t rush drilling for a few reasons.

Installing Bulkheads

Bulkheads come ready to install and don’t require any extra glue, etc. but some people add a lubricant to the rubber gasket. This generally isn’t needed. The only type suitable is a silicone based type – Never use any kind of petroleum based oil on the gasket.

How to Install: The gasket should be placed between the flange and the glass on the inside of the tank. You generally want to tighten the Nut to the point of contact, then go 3/4 of a turn past that point using a wrench if possible. Do not over-tighten, because the glass will crack. Once tight, it may be possible to spin the Bulkhead in the hole by forcing it, even though the seal is intact.

It is important to understand that when you drill holes in a piece of glass, the holes become a point where force concentrates.

The places where holes are drilled in a pane of glass, even with bulkheads installed, can become an Achilles’ Heel of the tank.

This just means that you should be careful with your tank, especially around the bulkheads.

Avoid a catastrophic crack on your tank by understanding what forces are at play
When we install standpipes and lengths of PVC to the bulkheads, they can act as levers. Levers that have the potential to place strong lateral forces on the glass if pressure is applied. Enough force, and a crack can happen. This is unfortunately more common than you might think in the hobby.

Practical ways to protect your tank

  • Never allow the tank to rest with any part of its weight on a Bulkhead such as during moving. Remove the bulkheads first or support the tank otherwise.
  • Take care not to pull, bump or place any force on the standpipes in an overflow for example.
  • Leverage and forces on bulkheads are more pronounced with Rigid PVC. Flexible PVC or “Spa-flex” will absorb some force but still has the potential to stress bulkheads and glass
  • Supporting plumbing by attaching it to your stand with brackets is a good idea

These forces are also why adding bulkheads to any tank with glass thickness less than 6mm (1/4″) is a bad idea. Anything thinner simply does not have enough strength to stand up to normal amounts of force.

Gluing pipe to Bulkheads

Most (if not all) Bulkheads you will find are made from black ABS, not PVC. It is generally not advisable to join ABS to PVC using regular PVC cement, but I have done so many times. Never had a problem. There is a special cement for PVC to ABS connections that you can find if you are concerned.

On the dry side of the bulkhead, you may want to glue a short length of PVC (3-4″) to it. Then, glue a union to this short piece. Using a union here makes it easy to disconnect your drain hoses if you need to move the tank. Keep in mind that this will be semi-permanent, and the only way to actually remove the bulkhead will be to saw through the short length of PVC.

Leak test

It’s a good idea to test your system for any leaks by filling it with tap water then turning the return pump on. Before this, You can use an air compressor to blast air through the pipes to get rid of most of the shavings or sawdust that might be in there.

Observe the system again after a few hours to confirm all glued and threaded connections are secure and leak-free. You should also shut off the return pump to test the overflow and that you have enough sump capacity. With the return pump off, you can also mark the high-water point in the return pump sump chamber to tell you what the max-water level should be.

Doing a leak test helps flush out the system before you add your rock, fish and sand.