Aquarium SUMPS – The Rundown

Posted by on August 26, 2013 - one

SUMPS – The Rundown

By definition a sump is a pit or hollow in which liquid collects, in particular. (Wiki). If you are new to the aquarium hobby, you may have heard the word sump before. In the aquarium hobby, and even in professional setups like those in zoos and public aquariums the use of a sump is by far the most efficient means of moving water in your tank. Since this is a hobbyist website we will keep it “sumple.”

Sump in use with equipment. image via R2R member Poseidon

Sump in use with equipment. image via R2R member Poseidon

In the past, we have used hang on filters, canister filters, and even under-gravel filters to attempt to keep our reef tanks clean. However there seems to be something wrong with these styles that has lead us to use them as little as possible. The media within the filter, be it sponge, carbon, or biomedia, gets very clogged and fast! Without constant cleaning these can become detritus traps that ultimately lead to dirty water. On top of dirty water, literally, is where all the oils collect. When left untamed these oils can become quite thick and begin to house their own occupants. Even algae can start to grow at the surface. This leads to a substantial drop in light penetration and corals will suffer.

So if filters do not filter what do you do? REDESIGN!!!! As heartbreaking as it is to tear down a tank, the plus side always trumps the pain of saying bye to your corals and fish. You do not necessarily have to sell all your stuff, just store it out of the tank. If you have a smaller tank like a 20 gallon than a rubber maid tote makes a GREAT holding tank!!


A basic sump consists of the following:

      1. Drain from tank
      2. Plumbing from Drain to Sump
      3. The sump itself
      4. The return pump
      5. The plumbing from the return pump back up to the tank.
image via R2R member surfn

image via R2R member surfn


The sump will be where you put all of your extra equipment you do not want in your display. Heaters, skimmers, reactors, thermometers, probes, and what ever piece of equipment you want to hide.

So, now that you have all of your stuff out of the tank, it is time to design the sump itself and the means to get the water into it. This will require an understanding of a few things.



3.Beginner Plumbing Skills



This is your best friend and worst enemy. Gravity will always be there and it will always pull you down. It keeps our whole planet together, so do not try to fight it! Instead, use it to your advantage. A sump, by definition, will be below your aquarium somewhere, generally in the aquarium stand itself. To get the water from your aquarium into your sump you will need to think of your tank like a bathtub, sink, or even a swimming pool. On a bathtub that has the drain plugged you can only fill it up so far until the water makes it into the overflow drain near the top of the tub. You will want your aquarium to have this exact feature. Here are your options:

      1. Drill a hole in the glass, but make sure it is not tempered. See why here: Do Not Try to Drill Tempered Glass
      2. Use a siphon style overflow box, which can be more dangerous when improperly used or maintained. Some accept safety features like the AquaLifter to keep the siphon from breaking.


This is the ONLY WAY we get the aquarium to transfer water down to the sump. NEVER USE A PUMP OR IT WILL FLOOD!


The size of your aquarium, the space you have to add a sump, and the flow rate you want all work hand in hand. PVC pipe can only handle so much flow, so you will have to figure out a good match between the drain and the return pump.

For my 20g I have a 1 inch bulkhead in the back of the tank with a glass box around the opening, called the overflow box. Ideally you would have more than one hole drilled for safety purposes. The size of this opening (1-inch) will handle between 500-700gph depending on a few things. The lower the hole, the more pressure there is to push water through the drain. Mine is up at the top so I will say 500 just to be safe. This means I can use a return pump around 500gph. This is plenty for such a small tank, especially when my goal for Total Flow is 600gph.


In order to connect a sump to an aquarium safely, you will need to learn how to cut, glue, and fasten various types of pipe, hose, and fittings. These are my Must-Have Tools for Plumbing

      1. PVC Cutter
      2. Sandpaper
      3. Heavy duty Shears
      4. Rubbing Alcohol
      5. PVC Primer & Cement and Teflon Tape
      6. Tape measure or String
      7. Marker
      8. Drill and a bit about the size of a q-tip stick
      9. Rag
      10. Paper and pencil


First you will want to set the tank and the sump where you want them. Observe the negative space between the 2 places you will want to link. (DRAIN TO SUMP) or (RETURN PUMP TO TANK). I will use a string to measure the distance. A tape measure works, but I seem to go quicker with a string.

If you have to instal elbows anywhere then draw out the schematic for your design. Once you have the general shape of your plumbing take the drawing to the hardware store and pick up the pieces you need. Get extra, you can always return the parts you do not use when you are finished.

Pick a starting point. I always start from the top due to my knee injuries from soccer. Start cutting and dry fitting your plumbing, making sure to keep minimal bends or horizontal directions to keep gravity working for you. Water drops much faster, try to keep it as downhill as possible. When you finally make it to your end point, in my case the sump, mark the pieces and even number them so you can assemble it once more to glue.

With pieces marked at their desired positions, you should be able to start the assembly process. Here is my procedure:


      1. Sand both surfaces to be glued with fine sand paper
      2. Paint a thin layer of PVC primer on the sanded area and let dry
      3. Apply the PVC cement to both surfaces
      4. Insert pipe, twist, and hold
      5. Rinse and Repeat until all fittings and pipe are assembled 


      1. Wrap the tape around the male threaded fitting the opposite way of the threads.
      2. When you think you have enough, double it.
      3. Screw the fitting into the Female Threaded fitting


The next thing to look into is how the overflow box will connect to the sump. Using PVC will be more efficient than using corrugated flex hose, and much more silent. If possible use as little elbows as possible and when a right angle is necessary use 2×45* elbows rather than a 90 to keep the friction to a minimum. The plumbing can connect to a bulkhead on the sump or you can route it straight into it, depending on your specific model or design. This one is connected via bulkhead.

Now we are connected to an empty tank, we are now ready to figure out the return plumbing. With 2 right angles and a 1 inch bulkhead at the top of the tank, I feel it would be wise to drop the pump size in half. I am going to use a 240gph pump and make up for lost flow with a powerhead within the display tank.

The distance from the pump to the tank will reduce the flow a little (or a lot if you have a basement sump like I have on my 90 gallon). Check the manufacturers flow rate charts for head pressure, it should also contain a chart that shows you flow rates through different pipes. If the pump you want does not have that information than it would be a good idea to look for a pump from a more reputable company.

The plumbing from the return pump is usually done with flexible hose to reduce friction. You can have the plumbing loop over the top of the tank like a canister filter:


Or you can drill a smaller hole for a return dedicated bulkhead, which most reef ready tanks have.


The return line will need a pinhole drilled into it just under the surface of the waterline, or at least have the outlet near the top, this will help minimize the siphoning backflow caused when you turn the pump off or experience power outages.

Now that the drain is connected and the pump is plumbed, it is time to fill it up to test. Doing the first test should be done outside if possible, as there is a chance you could have a leak or made a mistake somewhere. This is how I test my builds:

      1. Fill the display until it starts to drain.
      2. Check for any leaks from the bulkhead, the plumbing, or the tanks themselves.
      3. Watch the path the water takes. This will help you understand how the sump works.
      4. Once the water makes it to the pump stop filling up the tank.
      5. Let the water from the display stop trickling down the sump.
      6. Fill the sump as full as possible, mark this level FLOOD
      7. Turn on the pump.
      8. The water will shoot up to the Display and begin draining shortly after.
      9. Check all the connections for small drips and leaks.
      10. Mark the sump MAX ON During this time, as this will be the MOST you will fill it.
      11. Now start taking some water out of the tank until the pump starts making a whirlpool and sucking in air. Fill the sump back up just until it stops and mark MIN ON
      12. These 3 marks will help you keep track of flooding, but it will also help you to eyeball evaporation.
      13. Turn it off to simulate a power outage
      14. Make sure to watch the return line. The siphon should stop as soon as the hole hits air.
      15. Turn it back on and off a few times, making any adjustments or fixing any leaks you can.
      16. Dump it and take it in to setup permanently.


At this point you got terrified of the concept and workload or have a display tank and an empty sump. What goes in the sump is up to you. No tank on earth, even in the same house, has the same chemistry. One tiny factor can mean the difference between designs.

When in doubt, start a thread! Like any issue you have, many others have probably had the same thing. Do not be afraid to ask, in fact you will be thanked by many and helped by the best.

If you have questions please start a new topic here in the Equipment Forum.






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One Response to Aquarium SUMPS – The Rundown

  1. Pingback: 40 breeder sump(Im new and lost) - Michigan Reefers

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