In this article I will explain how to build sumps, bulkheads, and the Durso Standpipe.
A sump is a water reservoir which is at a lower level than that of the tank. Gravity is used to cause water to drain from the main tank to the sump. A pump is used to move water from the sump back to the tank. This creates a continuous flow where all water in the system passes through the sump. And then you can fit the sump with a filter or have the sump run to a filter.
As discussed in the article Plumbing FAQ, there are several advantages to having a sump. First of all, sumps provide an extra compartmentalized space where you can put your equipment so that it doesn't clutter up the main tank (heaters, chillers, filters, etc.). They also provide additional water volume, which provides for additional dilution of nitrates and additional temperature stability. They enable additional circulation and gas exchange by providing a greater amount of aeration to the water. Sumps also act as protein skimmers because they take off the oily film that forms on the water surface. They do this by pulling the water from the top of the tank, not the bottom like many filtering systems. Another advantage that sumps have is they will always keep the water level in your tank constant, so your fish will always have the maximum amount of swimming space possible. Sumps are also nice because instead of adding concentrated amounts of chemicals to your water, you can add them to the sump, which will dilute them before introducing them into the main tank.
Building Your Sump
Before you being building your sump, you'll need to be familiar with how to make bulkheads. Once you know how to do that, you'll be ready to start building your sump. You can build two kinds, really. You can use your sump to act solely as an overflow chamber, in which case you will need to use a bulkhead. That's because the water will continue on to either a filter or another sump below your tank. The other kind of sump you could build could function as the filter itself. Let's first address building a sump that functions as an overflow chamber.
You can use either glass or Plexiglas to build your sump. Each has its advantages. Glass, for instance, is cheaper. Plexiglas, on the other hand, is more sturdy, easy to cut, seal, and drill. There is also a wide variety of translucent and opaque colors of Plexiglas. I prefer to use Plexiglas (a.k.a. acrylic) over glass because I can drill holes along the top for the water to flow through instead of having to construct something out of some other material as I would with a glass overflow chamber. That is what I had to do with my 75-gallon tank because it was given to me with a glass box already. In that case, I used eggcrate to prevent fish from being swept over the top and into the chamber.
If you are using glass, you will seal the pieces together using silicon. Make sure that you are using 100% silicon. If you are using acrylic, you will use Methylene chloride (available anywhere Plexiglass is sold - see Working With Acrylic.), which actually melts the two pieces of plastic together. Be sure and drill the holes along the top before you melt the pieces together. I made this box pictured below using acrylic scraps from a plastics manufacturer's bargain bin, and then trimmed them down to a uniform size. The Methylene choloride is great because it joins the pieces together as if they had never been more than one piece.
If you are using acrylic, it is best to make your box and to let it dry for 24 hours before you glue into your tank. If you are making a glass box, it is easiest to glue it all once. Whether you are using acrylic or glass, you will need to use 100% silicon to glue the box to the glass aquarium. (Acrylic tanks would need Methylene chloride for acrylic boxes.) I get ready by setting the box into the tank and then using a crayon, mark its position on the opposite side of the glass. This lets me know where to apply the silicon caulking and the crayon can always be scraped off afterwards. I then remove the box, apply the silicon on the line, and then place the box onto the bead of caulking and frimly push it to the glass. It is important to push any silicon that has been pushed away back into the seam. Let the silicon dry for at least 24 hours. NOTE: The silicon and Methylene chloride are very toxic and it is important to work in a well-ventilated area.
Before we talk about building a sump that functions as a filter, let's finish talking about our sump that serves as an overflow chamber. Most saltwater setups come "reef ready." That means that they come with one or two of these overflow chambers that we have just built. And inside these boxes is an intake tube, or what's called a standpipe. These usually are a perforated tube or an uncapped PVC pipe, which allows the water to flow into the standpipe very quickly. And with the water goes lots of air, which creates an awfully loud gurgling noise, something akin to someone blowing their nose or a toilet flushing. Running 24 hours a day, that can get very annoying, very quick. These standpipes are usually designed such that they permit the water to drop some 15 inches before reaching the level of the standpipe's intake, which creates a loud splashing noise. This means that the water level in the overflow chamber is usually no higher than 3 inches deep.
About a year ago I came across Richard Durso's Saltwater Page. He developed a unique standpipe design that remedies these problems. This involves using a solid standpipe with a submerged intake (see the picture above). The intake needs to be placed as high in the sump as possible, and a hole needs to be drilled in the cap, which allows for self-priming. This design is superior to ordinary designs because there is little to no water fall, converting the chamber into a refugium, it is whisper quiet, with no splashing or gurgling, and the chambers don't drain in a power outage. Plus the pipe is self-priming! And how much for this simple design? About $5, not counting our homemade bulkheads.
The possibilities with this design are endless. You could use this for internal overflow boxes as well as hang-on-the-back skimmer boxes. If you are interested in building this standpipe, I would encourage you to visit Richard Durso's web site where he has documented several adaptations to his original design. He also sells ready-made kits, but why buy it when you can make it yourself? My purpose here is only to show you the advantages to this standpipe's unique design and show you how to make it.
You might have noticed in the picture above that I have two pipes fitted to two bulkheads in the overflow box. The pipe on the left is obviously the intake. The second pipe could be used for return flow or even a back up intake in case the first gets clogged (unlikely and unnecessary).
The Biological Filtration
An overflow chamber, or sump, can also be constructed to serve as a biological filter. Here is an idea that I designed originally for my 10-gallon fry tank, although I later adapted it for my 20-gallon fry tank.
I drilled holes along the top of this black piece of acrylic and then used thin pieces of Plexiglass to create compartments behind the holes, where the water will have to pass through sponges before entering the sump. These sponges will act as biological filters. In order to keep them functioning, clean them out with a little bit of tank water siphoned from a water change. Tap water (especially if hot) might kill the bacteria, which would disable the biological filtration. I glued this piece into the back of my tank, leaving a small space between it and the back wall of the tank. In this internal sump I have placed a Rio 800 submersible pump. This pump has an air intake, which helps to aerate the water. The pump then returns the water via a spray bar. I have drilled a lot of holes in the spray bar so that the spray won't be very strong. You may have noticed that I have a clear piece of acrylic attached at a 90-degree angle. This setup is for my fry tank, which has fry at all different stages of development. So, I put the divider in to separate the older fry from the younger.
This biological filter could easily be further developed. For example, you could put another piece of acrylic in the sump to divide it into several more comparments (see above). You could set these comparments up such that water would have to flow sequentially from one to the next. In these compartments you could put the small sized bio balls, or carbon packets, etc. The options are limitless. I just wanted to give you a sneak peak at some of the possibilities. □
Disclaimer: By building this DIY project you agree not to hold the author or the owners of this Web site responsible for any injury or bodily harm you may cause to yourself or others. Always wear safety glasses when working with tools and keep chemicals and power tools away from children. Read and understand all safety instructions pertaining to equipment prior to use.