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DIY Overflow Skimmer and Sump Tank
by MudbugnLouisiana

Before I get started on this procedure, I must tell you that the white stuff you see in the box is filter media just to help quieten down the gurgle from the spillway. Do not remove the scratch proof paper from the acrylic until everything is bonded together. Before you attempt any gluing or bonding do some test pieces for practice.

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How To Build the Overflow

To build the overflow I used 2 small sheets of 3/16-inch acrylic and a 1-inch plastic siphon tube from the skimmer to the overflow. I also used Flotec 1¼-inch black sump pump discharge hose and a metal hose clamp. A 1¼-inch male PVC adapter is used to connect the hose to the bottom of the overflow box. A 1¼-inch female is inside the box with a rubber gasket on the male side to seal the overflow watertight. A cylindrical prefilter element just like the ones in a pre-made overflow tank can be purchased through your local pet store or on the internet. A 1-inch piece of PVC 3-inches long will be needed later to attach the sump hose. You will need a table saw to cut the acrylic sheets the right sizes. The blade on the saw must have straight teeth and not crosscut teeth. If you try to use crosscut teeth you will ruin the acrylic. Set the teeth on the blade just above the acrylic sheet to make your cuts. Push the sheets through without stopping nice and smooth.

Remember to measure the front and back of the fence on your table saw before cutting each piece. If any 2 pieces of acrylic do not fit together they will not seal. Please test fit all the pieces before bonding them together.

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First, cut 1 piece of acrylic 10½-inches tall and 6-inches wide for the back. Cut another piece 18½ tall and 6-inches wide for the front of the overflow box. The 18½ piece must be bent with a heat gun to allow the overflow tank to hang onto the aquarium. This 18½ piece also serves as the backside of the skimmer box, which sits in the aquarium. Refer to all the pictures if this is confusing you. With a straight edge like the end of a table you must clamp the 18½ piece to the top and bend it in the shape of the letter U but instead of rounding the bottom make it square. Now one side of the U will be 6-inches and the other side of the U will be 10½-inches with the bottom of the U being 2-inches.

Please wear gloves at this point, as the acrylic will have to be heated until it is flexible. Please get some thinner pieces of acrylic and practice this step. Don't blame me if you mess up because you didn't practice first. Using something hard and flat -- like a piece of flat bar or a piece of wood -- bend the acrylic into a square U with a 2-inch section at the bottom of the U. If you do not want to hold this until it cools just clamp it to the table. Also, if you mess up just reheat the acrylic and rebend it. Now cut a piece of acrylic 6-inches wide by 4-inches deep. This piece is the bottom of the overflow box. Now cut 2 pieces of acrylic 10½-inches tall and 4-inches wide for the sides. This overflow box has a divider in the middle for the plastic siphon tube and the prefilter element. You will need to cut another piece of acrylic 8-inches tall by 4-inches wide to make the divider.

To join the acrylic you can use a couple of different methods. You can use IPS Weld-on 16 and thicker or just Oatley PVC Cleaner. I prefer to use Oatley PVC Cleaner since it is cheaper and it is thin like water. You will need a small bottle with a syringe tip to apply the PVC Cleaner if you go that route. IPS Weld-On comes in a tube which you can get needles for.

You will need a hand block sander with 120 grit paper to get the imperfections out of the edges. If needed use a small file also. Make sure you sand and /or file until the edges fit together almost perfect. If you have any gaps then sand until the gaps are out.

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If the gaps are too big then you will have to fill them otherwise the overflow will leak. If you used Weld-On to bond the acrylic just go with a thicker viscosity brand of Weld-On. If you decided to go with Oatley PVC Cleaner just scrape some clean shavings from another piece of acrylic and mix the 2 together. The more shavings you put the thicker the viscosity will be. Make sure all your acrylic pieces fit at 90-degree angles with the bottom and back pieces butted on the outside. Make a 90-degree jig to hold your pieces in place while the solvent dries. Clamp the pieces together while they dry with wood vises or clamps. Apply your Weld-On or PVC Cleaner with a syringe until the acrylic turns clear. When the acrylic turns clear you have enough solvent. Let the pieces dry for at least 20 minutes before checking the bond with PVC Cleaner. If you used Weld-On follow their recommendations.

After everything is assembled and the solvent has dried you can fill the overflow with water to check for leaks. Just clamp it together and add more solvent if it leaks. The divider piece goes directly in the middle of the overflow box. Now it is safe to remove the scratchproof paper from the acrylic.

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To hold the 8-inch tall by 4-inch wide divider in place you will have to glue it in place with a tube of aquarium silicone. There is no easy way to glue this in place because you only have 3-inches on either side to place your hands inside the overflow box. A small clear hose will work if your fingers are too big.

Once everything is dry you can drill a hole at the bottom of the chamber opposite of the 1-inch plastic siphon tube. This is for the 1¼ PVC male adapter to clamp the Flotec 1¼-inch black sump pump discharge hose to for the sump tank. I suggest you use an air drill set with low pressure or a chord less drill because you will need to pour water on the acrylic to keep the drill from biting. You can purchase the 1-inch plastic siphon tube at your local pet store or on the internet. A 1¼ PVC female will be used inside the overflow tank to hold the 1¼ PVC male in place. Do not screw them together until you have the gasket in place and you are ready to do final assembly. They sometimes cannot be unscrewed once put together. I use a beveled rubber gasket on the bottom of the overflow box to seal the 1¼ PVC fittings together and make them water tight. Glue a 1 -inch PVC pipe 3-inches long into the male 1¼ PVC adapter. This will give you something to hoseclamp the 1¼-inch black sump pump discharge hose to. The cylindrical prefilter can be put on the female 1¼ PVC when you are done. With all this done we are ready to move on to our skimmer box!!

How to Build the Skimmer Box

The skimmer box will need 2 sides, the front, the back, the bottom, a pair of ¼-inch nylon bolts and a pair of nylon wingnuts. Cut all your pieces on a tablesaw, sand and then bond them with whatever you chose to build the overflow. You will need to cut 2 pieces of acrylic 6-inches tall by 6-inches wide for the front and back.

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Now cut 2 pieces of acrylic 6-inches tall by 3-inches deep for the sides. Bond all the sides together as you did with the overflow and let dry. It is time to make the drain passages for the skimmer box. Set your table saw blade 1-inch high. Turn the skimmer box upside down and begin cutting 1-inch deep slits in the front of the skimmer box. Evenly space the slits ½-inch from each other. Now do the same thing for the sides. You will only need 2 slits in the backside of the skimmer and these are only used to hold the skimmer box to the overflow box with the nylon bolts and wingnuts. Make 2 - 1½-inch slits spaced 1½-inches from the sides in the back part of the skimmer box. You will have to put your overflow box in the aquarium and figure out where your water level will be. The slits for the nylon bolts in the skimmer box should be placed ½-inch into the water and mark a spot also ½-inch down on the overflow hanger below the water level also. This will allow you to be able to have some adjustment up or down with the skimmer box. Now with a ¼-inch drill bit drill the holes in the overflow hanger to hold the skimmer box in place. Make sure to use hex head nylon bolts because screwdriver head bolts are hard to tighten up with the light cover on the aquarium. Now you are finished with the skimmer box.

How to Build the Sump Tank

For the sump tank you will need either a 10 or 20 gallon aquarium, a 1¼ PVC male terminal adapter, a 1¼-inch female screw on lock to hold the male adapter, a rubber gasket, a sheet of small plastic lighting eggcrate, filter floss, a sheet of plastic breeder screen, aquarium silicone, however many bio-balls it takes for your aquarium and a sheet of acrylic for a cover and to make eggcrate holders.

How do you know what size aquarium to get for the sump? 10 or 20 gallons? That will depend on the size of your aquarium and how you want to set it up. A good rule of thumb is this: 1 gallon of bio-balls takes care of 30 gallons of fresh water.

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On the other hand, 1 gallon of bio-balls also takes care of 20 gallons of salt water. I used 2½ gallons of bio-balls for my 55-gallon aquarium. That will take care of 75 gallons of fresh water. If you divide a 10 gallon aquarium in 2 you get 5 gallons, so I figured the 10 would be great for my setup. Now if I built another sump tank I would go with a 20 gallon long for the simple fact that I could put a submersible heater in there where as the 10 gallon is too small to fit my heater.

To start, cut your sheet of acrylic on your tablesaw the same size as the 10 or 20-gallon aquarium. This is going to be the lid for the sump tank. You may also bond some of the left over pieces of acrylic together to make a handle for picking up the lid. Cut another sheet of acrylic 2-inches shorter and the width of the aquarium. This is going to be the divider. Now glue the divider 2-inches off the bottom with your aquarium silicone. This is going to allow the water to pass through the bio-balls and get to the return pump. On the left side of the aquarium cut the plastic eggcrate to fit in the bottom. Keep adding eggcrate until it is higher than the 2-inch water passage under the divider. The purpose of this is because the bio-balls need to be higher than the water level in the sump tank. Now cut 4 pieces of acrylic 1-inch tall by 4-inches long. This is going to hold a sheet of eggcrate up above your bio-balls so you can put a couple sheets of filter floss to filter your water a little further. Glue the 4 pieces of acrylic catercorner to the 4 sides of the aquarium with aquarium silicone.

After the silicone is dry, add your bio-balls and cut one piece of eggcrate to fit on the top of the 4 corner pieces. Cut a sheet of plastic breeder screen with the small holes the same size as the eggcrate you just cut. This will help to disperse the water evenly over the bio-balls as it drips through the screen. Now if you do not have filter floss wide enough to put on the top of this, here is an idea for you: Go to Wal-Mart and buy a 15-inch by 10 foot roll of snow cover blanket in the craft section. This is made of 100% Polyester and is exactly the same thing filter floss is made of. Cut 3 to 4 sheets of polyester to put on the top of the breeder screen. Now cut another sheet of plastic eggcrate to place over the polyester to help hold it down.

Now cut a hole in the middle of the lid on the left side for the 1¼ PVC male terminal adapter. Silicone your black sump hose from the overflow inside the 1¼ PVC male terminal adapter. Once this is dry you may put rubber gasket on the top of the lid and place the 1¼ PVC male terminal adapter into the lid. Screw the female adapter to the male adapter to hold it in place. On the right side of the sump tank place a submersible pump rated 5 times the size of your aquarium to return water back into the aquarium. Again, cut the lid to fit your connections on your submersible pump for however you decide to plumb the return lines.

That's it, now you have the satisfaction of having made your own overflow and sump tank without spending $250 US. I have to give my sincere thanks to my buddy Red Dog for building the first one like this and helping me build mine. Without his help I would have never completed mine.

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.
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