DIY Plumbing 101

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Original article - Denise Skidmore and forums. Reproduced with permission.


The inspiration for this how-to came from a discussion between Leona and Squidd on's message boards. In short, Leona wanted to upgrade her aquarium, and Squidd provided a lot of the advice and data necessary to build a good one. Much of the info in this summary came from Squidd.


I'm afraid there are no quick and easy answers to the question: "How should I plumb my x gallon aquarium?" There are many things you need to consider. What are you keeping in the aquarium? What kind of equipment do you want to run? Do you want to work with your existing aquarium, or order a custom one?

We will tackle each of these questions in the various sections below. You really need to understand each section before you make your decisions. All of the decisions are interrelated. If you decide to increase your goal flow, you might need a bigger pump, that needs a larger pump chamber, or a drilled hole.

If you decide you need more pods, you need to increase your refugium, which increases the size of your sump, increases your refugium goal flow, and could decrease the amount of water going back up to the aquarium, affecting your display tank goal flow.

Read on for the full scoop, and then you'll have the info you need to understand your own plumbing situation, and plan a good aquarium and sump.


Water Flow[edit]

Water flow in aquariums is usually measured as a multiplier of the volume of the tank. Example: a 38 Litres (10 US G.) aquarium with 10X flow has 379 Litres (100 US G.) per Hour pumped through it. For a basic reef aquarium with softies and fish, you are aiming for over 10x flow. For an SPS reef, you are aiming for 20x-30x flow.

Water current[edit]

Some corals benefit from shifting currents. This can be obtained in several ways, but the easiest is through a wave making device. There are two common types of wave making devices. The simplest switches power between several pumps, so different pumps are on at different times.

This is the easiest to set up, but will cause the pumps to wear out faster than they would in constant use, and clutters up the aquarium with extra power heads. The second method is to have multiple returns on a closed loop system, with a device that moves the flow from one return to another. This is the most efficient method, but requires a custom drilled aquarium.

Nutrient Removal[edit]

One of the ways to set up a refugium is with a light and nutrient removing organisms. For this purpose the refugium should have a decent sized footprint and span the sump in one direction for easy lighting configurations.

Pod Production[edit]

The other way to set up a refugium is for pod production. For this purpose total volume counts more than shape, and you will fill the space with live rock and sand.

Skimmer efficiency[edit]

Most skimmers work best in a set depth of water. A sump with baffles can easily arrange for a constant depth of water for the skimmer.

Bubble removal[edit]

In addition to the bubbles the skimmer lets off, the overflow will also produce large quantities of bubbles. Removing these bubbles before the water returns to the aquarium is both more appealing to the eye, and healthier for some organisms such as sponges.

Propagation space[edit]

If your corals are already doing well, you may want space for baby corals to hang out without cluttering up your front sand. This will not be discussed in detail, but the requirements are similar to that of a refugium. (Lights, lower flow.)

Aquarium Types[edit]

Reef Ready[edit]

A "Reef Ready" aquarium is a drilled aquarium, with the overflows already installed. It must be used with either a wet/dry filter or a sump, as otherwise you will be forced to under fill it to not have water falling out of the aquarium. This is the best setup for someone who wants to minimize their plumbing and planning. The holes and overflow should already be planned for a decent flow rate. Be sure to note down what flow the overflow is rated for, this will affect your sump turnover and return pump decisions.


A "drilled" aquarium is a standard aquarium with appropriate holes in it. You will need to buy an overflow kit and bulkheads to make the aquarium functional. If you have a selection available, make sure to choose the overflow kit with the appropriate flow rating. (More on what the "appropriate flow rating" is later.)

Custom drilled[edit]

Unlike the other aquarium selections, if you get a custom drilled aquarium, you may want to plan it last instead of first. After you make all your plumbing decisions, it will be pretty obvious how many holes you need drilled and where. If you get your custom drilled aquarium from a glass company, you will likely have to install your own overflows and bulkheads. If you get it from an aquarium company, you can have them installed for you.


A standard aquarium is just a glass box, like you will find in any pet store. You will need an overflow box to run a sump off of a standard aquarium. This is the cheapest, but least desirable option, as overflow boxes can fail, causing a large, expensive, watery mess and a burned out sump pump.


The stand you choose or build may play a big part in how you set up your aquarium. Is there enough clearance for your skimmer? Is the center support or a side panel removable so you can fit a large sump inside? Do you want a third level for an overhead refugium/dosing tank/surge tank? Will it take the weight of both the display tank and the sump? This is a plumbing discussion, so we will not cover stand design in detail. Just be aware that your stand can affect plumbing.

If you have already selected your stand, and it's a bit troublesome, consider dividing the sump into two separate tanks. One could house your refugium and skimmer, the other the bubble baffles, back flow area, and return pump. A hole drilled in each one would allow you to plumb the two together once they are in your stand.

Using two tanks to fit more sump into an annoying stand


What is a sump?[edit]

A sump is a water basin below the aquarium that water is allowed to fall into and then from which the water is pumped back up to the aquarium. A sump can be a spare aquarium, a wet-dry filter, a rubber maid tote, or if you want to go overboard, a lagoon will do nicely.

A sump is usually located in the stand under the aquarium, but can also be located on the other side of the wall, or in the basement, for concealment of large sumps.

Basic Sump, we will add more chambers

Why do I need a sump?[edit]

There are several major advantages to having a sump.

All filtration, heating, and dosing equipment can be hidden away with the sump. When properly plumbed, the water level in the display will remain constant. All evaporation changes will show in the sump. (You can hide your auto top-off under the stand too.) Your total system volume is increased. This increases the stability of your water, and therefore your ability to recover from mistakes and disasters. It makes a convenient place to put a refugium. (More on them later.) With the use of baffles, you can make a chamber that always remains at the ideal water height for your skimmer. With the use of baffles, you can almost eliminate the bubbles generated by your skimmer.

How do I size my sump?[edit]

Most of the time in saltwater, bigger equipment is better. You do need to consider the spatial confines of the place you are putting the sump. If it's going under the stand, then you need to figure out how to get it in there. (Some stands have center braces that make it difficult to put large sumps inside.) If you are putting equipment in the sump, you need to make sure there is clearance above the top of the sump to service that equipment. At a minimum, the sump must be able to hold the different chambers you decide you need. These chambers will be addressed in detail later, but in summary they are: refugium, skimmer chamber, bubble baffles, return pump chamber, and back flow space.

Overflows and overflow boxes[edit]

What is an overflow or overflow box?[edit]

An overflow is a chamber of your aquarium where water will run over the top, and drain out a pipe in the bottom. An overflow box is for non-"drilled" aquaria, and performs the same job by means of a siphon over the edge of the aquarium, leading to an overflow inside the box. Both objects perform the function of keeping the water level in the aquarium constant given a water source.

Why do I want an overflow/overflow box?[edit]

There are several methods of getting water from the aquarium to the sump: siphon, pump, and overflow. Both the siphon and the pump have the problem that it is difficult to balance the water going out of the aquarium with the water coming back in. You don't want either your aquarium or your sump to overflow, while the other runs dry. An overflow or overflow box will allow the passage of exactly as much water as is being pushed back up to the aquarium. It is your insurance of a smoothly operating sump.

How do I size my overflow?[edit]

The overflow should be rated to carry slightly more water than your pump can push at the "head" rating you are using. (See more under pumps.) Having too large an overflow will mean extra air bubbles and noise in the system. Having too small an overflow will mean water all over the floor. (I vote for bubbles.)

Reducing the failure rate of overflow boxes[edit]

To reduce the chance of failure, get an overflow box with a rating only slightly higher than what your pump is pushing. The fast flow through the box will prevent the buildup of air bubbles that can break the siphon. You can also purchase a vacuum pump that will suck out the air bubbles as they form. The ultimate solution is of course, to go for a drilled or reef ready aquarium and not have an overflow box at all.

Reducing the noise level of overflows[edit]

You can reduce the noise level of an overflow by using a stand pipe. A stand pipe is a pipe that raises up from the overflow drain almost even with the outside water level. There are a few different designs of stand pipe, but they both work on the principle of having an under water intake and only a small hole for air to pass through. (Without the hole, the stand pipe would turn into a siphon, too large a hole will make for a noisier stand pipe.) The two most popular are Durso and Stockman stand pipes.

The Durso has a pipe coming up through the overflow drain almost to the water line, going into a T. The right of the T goes to a street elbow, facing back down into the water. The top of the T goes to a short segment of pipe with a cap. The cap can be vented in a variety of ways. The original durso just had a tiny hole drilled in the cap. Later modifications suggested were air valves and matching slots in cap and pipe so that the cap could be rotated to adjust air flow. The Durso is probably the easier of the two to assemble.

The Stockman drain pipe is perforated at the water line. A bushing is modified to be able to push down over the pipe backwards just above the preformation. A coupler or pipe segment goes over the bushing, shielding the perforated section of the pipe from open air contact. A cap goes on the very top, again with a small air hole. The Stockman can fit in a smaller space than a Durso can.

When deciding at what height to place your stand pipe, remember the water level in the aquarium is set by your overflow teeth, not the stand pipe. Moving the stand pipe lower will increase it's flow capacity, moving the stand pipe higher will reduce noise levels. Placing the stand pipe above the overflow box teeth will be completely pointless.

Drilling and bulkheads[edit]

So, your tank isn't drilled but you'd like it to be. This can usually be solved. There is some risk in drilling glass, even professional glass shops will not guarantee the glass will not shatter. That being said, the professional glass shop may be your best bet for drilling your holes. Drilling the hole yourself requires a special bit and or grinding compound and coolant, a very steady hand or drill press, and patience. There are other resources better than myself for details on glass drilling if you are the adventurous type. Look for them. My only major advice is to avoid drilling tempered glass, it will likely shatter. Most large aquaria have tempered bottoms. Read on about bulkheads before you decide what size to drill your hole.

So, you've bought a drilled tank or had yours drilled, and you want to plumb it up? Your solution is the bulkhead. A bulkhead is made of two pieces that screw together from each side of the glass wall. A gasket or two makes the seal water tight. The bulkhead will either be a slip fitting, or a threaded fitting. From the bulkhead fitting, you can connect to normal PVC plumbing. Note that a 1" bulkhead hardly measures 1" anywhere. Standard PVC 1" pipe has an outer diameter of 1.32", so the inner diameter of the bulkhead is 1.32" and the hole the bulkhead fits in must be larger than that. Either get good specs on your bulkheads, or order them, before you decide how big to drill the hole.

Example bulkheads and hole sizes
Fits Pipe Hole Size
½ 1⅝
¾ 1⅝
2" 3"

Pipe and Fittings[edit]

Why PVC?[edit]

Much of your house plumbing is made of copper, and there are often more copper fittings available than PVC; however copper is toxic to marine invertebrates. Brass is an alloy of copper, so the same applies there. PVC will not leach anything undesirable into your water, can be worked with wood tools if pipe cutters are not available, and glues or screws together rather simply.

When gluing PVC pipe, you need purple primer and cement. Some specialty pipe, like clear PVC or flexible PVC may have different glue requirements, so pay attention to manufacturer directions.

Some people think clear PVC is neat, and just like using it. It is however very expensive, and allows the growth of algae on the inside of the pipe. It can be useful in places where you want to be able to observe bubble buildup.

Flexible PVC, also known as spa-flex, is rather desirable for long runs, as it reduces the need for fittings. When the pipe bends slowly around a curve instead of going through an elbow, it reduces the friction in the pipe, and allows for greater flow.

When purchasing pipe, inspect it for cleanliness and uniformity. If the stamp marks on the outside bothers you, you can sand it off after assembling your pipe.

Pipe Sizing[edit]

It is important to size your overflow bulkheads and pipe correctly. Pipe that is too small will restrict flow, cause premature pump wear, and cause overflows to not run fast enough. Pipe that is too large will cause air bubbles and excess noise.

The chart below shows the flow rating you can expect from a stand pipe or drain of the given size. A U-tube of the same diameter will run slightly slower. Note that pipes can be paired up for increased flow (two 1" drains will carry a total 1200 gph). Try to select pipe that will carry slightly more than the expected flow rate.

Stand pipe Size Gravity Flow Rating
¾" 330 gph
1" 600 gph
1¼" 910 gph
1½" 1300 gph
1¾" 1800 gph
2" 2350 gph
2¼" 2960 gph
2½" 3650 gph
2¾" 4450 gph
3" 5280 gph

Fittings and Head Loss[edit]

"Head" is the term used to describe the distance between the water level in your pump chamber, and the water level in the aquarium. The more head you have, the harder your pump has to push. More on how head affects pumps later, for now we need to discuss factors in calculating head. In addition to the straightforward measurement of height, you also need to count up your pipe length and fittings, and add up the friction they cause.

The friction head loss on pipe is nominal for the 5 feet or so we run our pipe from the sump to the aquarium. This should however be researched if you have a remote sump. The friction head loss for fittings however, is significant. For each 90 degree elbow add about one foot of head. (More precise charts for fitting head loss can be found, if you wish to compute your flow more exactly, more research is required.)

Other Fittings[edit]

Although elbows should be kept to a minimum, there are many other fittings to consider to add functionality to your system.

  • Male/Female thread adapters

Extra pairs of male/female adapters can turn a rigid pipe system into one easily changeable at a later date. These are especially useful down by the pump where you'll need to make a solid, removable connection. You may consider getting some of your more expensive fittings in threaded form and put male thread adapters on the pipe. Then if you want to move the fitting or put it in a different system, you can simply unscrew it and use it again.

  • Union Fittings

A union fitting is designed for easy disconnection of two pipes. If you may be moving your tank at a later date, a union fitting on each pipe going in and out of the tank will make it much easier to separate plumbing from tank. A union fitting after a pump is even easier to remove than a threaded fitting, as you don't have to keep spinning the pipe or the pump in place. A true union valve is a valve with a union on each side.

  • Ball Valves

Although there are debates on the best type of valve to use on your saltwater aquarium, PVC ball valves are a relatively economical and useful solution, commonly used on saltwater aquaria. They are best used any time your pipe Ys and you want to control the relative flow. Avoid using valves to "throttle" your pump. If you must "throttle" your pump, add a T and a ball valve on the open side of the T. You can then let the excess water flow back into the sump, keeping your pump from prematurely wearing out.

Anti-Siphon Holes[edit]

Although tiny and practically free, anti-siphon holes can be an essential part of your plumbing. An anti-siphon hole is simply a small hole that allows air into the pipe in a vacuum situation. Such holes should be drilled quite small, and either at an air gap in the pipe (such as the top of a standpipe) or above or just barely below the water line inside the tank (such as on your return line.) The hole will leak, so place it with the direction the water should squirt in in mind. (Towards the glass, or off to the side are both popular.) This little feature added to your return line will ensure that in case of a power outage, only the water in the pipe will fall into the sump, and that the return line can not siphon out a significant quantity of water from your display tank.


Refugium AKA Fuge[edit]

What is a refugium?[edit]

In short, refugium is Latin for refuge, or a place to hide. The refugium is a place to grow organisms that are beneficial for your aquarium that would get eaten by the inhabitants of your display tank. Getting away from the original meaning of refugium, it can also be a place to put organisms that would take over the display if put there instead.

What size do I need?[edit]

Just like the display tank and sump, bigger is better. Unlike the display tank and sump, too small is better than none. A good number to aim for is 20% of the display tank size.

What goes in the fuge?[edit]

Refer back to the goals section now. Are you trying to lower nitrates? Are you trying to increase your pod count? Both can be accomplished by having a larger fuge, with a section for each.

Two lower nitrates, the fuge should have a small amount of live sand and live rock, and a large amount of macroalgae and/or xenia. A good light should be placed above the fuge, but doesn't need to be quite as strong as your display lighting.

The macroalgae and/or xenia should be trimmed/fragged on a regular basis, and the trimmings/frags removed from the system. (It's ok to feed some of the macroalgae to herbivore fish if you are replacing regular feedings rather than adding to regular feedings.) If you do not prune and remove, than no nitrates will be exported in the long run, and you stand a higher chance of a fuge "crash". A crash is when your macros/xenia decide they are too crowded, and start dissolving themselves in an attempt to distribute cells to other parts of the ocean. In your contained system, this means lots of excess organic matter in the water all at once, and can mean a big problem with your water quality. If you keep up with your fuge maintenance however, it will be a boon to your water quality over time.

For pod production, the fuge should be mostly live sand and live rock. A light can be helpful in growing phytoplankton, but zooplankton do not need light and can grow off debris coming out of your display tank. (Get the light when you can, but don't skip the fuge because a second lighting system isn't in the budget.)

If you have a deep sand bed, be sure to stir up small parts of it each time you do aquarium maintenance. Over time the whole sand bed should be stirred, to prevent a large buildup of gunk. If you do not stir up the sand bed, and have insufficient detrivores to do it for you, you risk a Deep Sand Bed (DSB) crash. A DSB crash is when a large store of organic waste is somehow re-exposed to conditions that cause it to start rotting and foul your water. To avoid DSB crashes you can either maintain your DSB, or keep only a shallow layer of sand and have mostly live rock in your fuge.

Closed Loops and other circulation[edit]

What is a closed loop?[edit]

A closed loop is supplemental water circulation that has both the intake and outlet submerged, and both intake and outlet are plumbed directly to the pump, with no air contact. A primary advantage to a closed loop is the pump will never lose it's prime. The closed loop piping will remain full of water even if the power goes out.

A closed loop is best implemented with a custom drilled aquarium, so the inlet and outlet of the loop can be guarrenteed to always be under water. It is also possible to have a hang on back closed loop, with the pipes going over the side and the ends completely submerged even in a power-out situation.

What else counts for supplemental circulation?[edit]

Power heads are the most common supplemental circulation, but any other hang-on equipment you have with its own pump can add to your goal flow.

Why separate main circulation from the sump?[edit]

Because a closed loop or power head is completely contained with no air, it makes considerably less noise than your sump pump, and will not introduce bubbles to the tank. If you put the full force of your circulation through the sump you will be fighting bubbles and noise all the time. Having supplemental pumps gives you some insurance if one of your pumps break down. Closed loops and power heads are also easier to install wave making devices on than your sump return line.

How much of the circulation should still go through the sump?[edit]

Your sump line needs to carry at least more water than your skimmer and fuge require. Look at the specs of your skimmer, and figure 3x - 6x fuge volume flow for the fuge. In the end, 3x to 5x display volume should go through the sump, and the remainder through your supplemental system. Overdoing the sump circulation causes excess bubbles and noise.


The first thing to know about your prospective pump is its performance curve. The performance curve tells you the expected water flow at given head values. There should be a little graph on the side of the box or product web site. That GPH rating in big type on the side of the box says absolutely nothing about how much water is still going to be coming out after the water has been pushed 3–5 feet back up to your aquarium.

For the sump pump, measure the distance from the top of your pump area to the top of your aquarium. Add on to that number one foot for each elbow in the pipe run from the pump to the aquarium. (Use as few elbows as possible to get around the back of the stand and over the side of the aquarium.)

For a closed loop pump, you only need to count elbows, you don't need to measure any distances. After you've calculated your rough head number, look on the chart for how much flow to expect at that head rating.

Without doing a full-blown pump review here, there are a number of things to look at when deciding on a pump.

  • Performance - How much flow will you get out of the pump under your conditions?
  • Reliability - Have you heard many complaints or recommendations about this pump brand?
  • Maintenance - Can you easily replace the impeller yourself? Are the parts readily available?
  • Noise level - Does it sound like a freight truck, or just a quiet hum?
  • Cooling - Is the pump air or water cooled? AKA is it submersible? Should it be plumbed outside the sump?
  • Saltwater tolerant - If the pump was not designed for aquaria, make sure it has no metal parts exposed to the water flow and can tolerate salt water.
  • Price - Obvious, but consider value before raw price.

Skimmer Chamber[edit]

The skimmer chamber is one of the simplest to compute. Your skimmer manual should contain a specification of the ideal water height it should be run in. If the ideal height is less than what you want in your sump, build a small platform. Place the baffle so that water must rise to a specific point before it can return to the pump chamber, in this way you can ensure the water level will remain the same in this chamber no matter how much evaporation occurs. Be sure to leave enough space for the skimmer's pump if that is separate from main sump circulation.

Back flow Area[edit]

Backflow space is any space inside the sump that is not normally full of water. It is designed to protect your aquarium and carpet in the case of a power outage. The back flow area should be large enough to hold all the water in the pipes should the pump stop flowing and all that water fall back into the sump.

The back flow area is typically between the baffled water line and the top of the sump. If each chamber has a different height, compute the back flow space available for each chamber separately, then add together. Ideally, you put in some type overflow that restarts after a power outage, and an anti-siphon hole in your return line, so between that and sufficient backflow space, you should not end up spilling any water, or damaging any equipment in the case of a power outage.

Layout and Baffles[edit]


In the diagram above is one possible way to lay out your sump. There are of course many ways to do it, but we shall discuss the pros and cons of several common choices.

Fuge in middle or on the side?[edit]

The fuge as the middle section requires very little plumbing and is quite popular. It's downsides is that you can not restrict the water flow to be less than that of the sump as a whole, and as a later chamber, it can not be deeper than the skimmer chamber. In the diagram we placed the fuge far to one side, with an adjustable water inlet. This allows us to dial in the correct flow for our fuge without changing the sump total flow.

Fuge water supply from drain or return line?[edit]

If your sump pump is a bit overpowered for the job, it may be beneficial to feed the fuge off of the return line rather than the drain. Decreasing the backpressure on the pump will prolong it's life. For increased pod production however, you may want to put "unskimmed" water directly into the fuge. Some claim that the skimmer removes nutrients necessary for pod growth.

Skimmer Platform[edit]

This one's pretty easy. Your skimmer needs to be high enough in the water to operate properly, and low enough it will still fit in the stand. The water level itself can be adjusted down somewhat, but you want to increase water volume, and margin for error in the pump chamber. If the water is too deep in the skimmer chamber after meeting all your other requirements, a platform is needed to raise up the skimmer.

Bubble Baffles[edit]

Bubble baffles are simply a set of baffles that force the water to move down and back up. The purpose is to remove air bubbles right before the return pump, so that the water returning to the aquarium has no bubbles.

Return Pump Chamber[edit]

The Return Pump Chamber will be the final chamber in any layout. All the water falls to this point. All evaporation changes should show up here, so this is where to put any float switches for an auto-topoff system. If you do not have an autotopoff system, mark where the water line should be when full, watch here for falling water levels, and top off as necessary. At the very least, the water in the return pump chamber should be deep enough to cover the pump or pump inlet bulkhead. Preferably it would be deeper in order to be able to tolerate some evaporation, and increase your water volume. Other than that, this chamber needs only be large enough to hold the pump.