A Large Wood Tank Project

by Bill "Pegasus NZ" of New Zealand

This topic is not a new one by any means. It was discussed fully on the Krib website way back in the early nineties, but my successful attempts were thirty years prior to this. As mentioned in my other article about making all-glass tanks, I take no responsibility for your actions. The tank described here stood for 4-5 years without problems or leaks.

You don't need to make a tank of glass, almost anything that holds water will do, take wood for example. In an emergency, or for breeding, use a drawer or any container, lined with poly. Just make sure the heater is safe... Back to the topic.  Some years back I built a tank of 4 feet by 4 feet by 4 feet, (1750 litres, 380 Imp. gals.) completely of wood, except for the viewing glass of course, which was 36" x 36" (600 x 600mm). For the ambitious among you, here's how I did it:

The frame as such was 3" x 3" (75 x 75mm) pine, and all joints were half-lapped or jointed and glued, and screwed with stainless steel screws. Note: avoid boric treated wood and such. My worst subject of all time was woodwork, and I managed, but seek help if you need to - it's a great deal of water once filled. Your aim is to create a complete box shape ready for the outer cladding, much like the old angle-iron framed tanks used to look like, without the glass.

For the cladding I used 35mm high density flooring board, but you may want to increase on this size or use marine ply if you're pretty well off. The front and rear top strips of 3" x 3" will tend to bend once the water is in, so put these the strongest way around, or use 4" x 4" if you feel unsure - the frame is never noticed and won't be seen, trust me. Avoid boards covered in laminates, as these over time can release toxins not good for your fish friends.

Note. All references to "Fastening" means screwed and glued. Glue ALL boards when attaching to the frame, and attach by screws only, no nails, and place screws not less than 50mm apart along each of the panels, all the way around. As the panel screws are on the outside, they don't need to be S/Steel, but must be at least one and a half times longer than the thickness of your boards. Fasten the base board first, (the bottom) to your frame making sure it doesn't protrude beyond the frame at any point. Dress up if required. Now fasten the rear board to your frame making sure it is flush with the framing, and again has no overhang. The sides, when attached will overlap the edge of the back giving a nice finish, while the front panel when finished (wait for it) will overlap the edges of the two sides. If you have the facilities, or can get it done, you can rebate or mitre the edges for a better appearance. (But I didn't, and mine looked great).

The front, when placed into position, should overlap the two side edges, and be absolutely level with the top of your frame. Now the tricky bit. You need to cut a viewing area into the front panel, (I used a jigsaw) and you may need help here. It can be square, or rectangular with rounded corners if you wish. I made like a picture frame of "L" shaped pieces to fit on the inside to hold the glass in position. These are really cosmetic, as the glass will be bonded to the front panel later, but my advice is to fit them as they help to avoid bowing. These "L" shapes should be rebated to slightly over the thickness of the glass so that when fitted they hold the glass much like a picture frame, but not be that tight that they squeeze all the silicone sealer out when tightened up. (see later) This rebated stock is a standard item at your local hardware shop. Use 2" x 2" if you can get it, it won't be seen. Just to clarify. These pieces go on the INSIDE of the front board, not the outside. The size of the viewing hole you remove from the front board should be smaller than the glass front you will be inserting. I made my hole 3" smaller all round, which gave the glass a good area to sit on and a good area for sealing. You could of course fit the glass BEFORE you assemble the front, but not a good choice in my view.

Fitting the front glass. I'm a bit of a daredevil when it comes to trying things out, and in my case I used ¼" plate glass, but if you're nervous increase on this. Note: clean the glass with meths or white spirit before fitting. Any dirt or finger marks could lead to leaks. Place the glass on the inside minus the "L" shaped bits. Position exactly where it will actually go and mark the area, not forgetting to allow the correct margin all way around. Now apply a good amount of silicone sealer to the area of the front panel inside your marks. Go on, shove a bit more on. Now get the help of your mum, or someone, and gently lower the glass into position. Don't worry about the sealer spreading for the moment, just make sure the glass front is where it should be. Just a note. The Krib site states that the silicone sealer will not adhere to the wood. I don't want to start a discussion on this subject, but mine sealed and adhered perfectly, as stated, for 4-5 years untouched.

NOTE, VERY IMPORTANT. When placing the glass inside, imagine you are glazing a window. Push too hard and all the putty spreads out leaving areas to leak. It's the same here. You are aiming to create a thickness of sealer around a ¼" thick or more between the glass and the front wooden panel. You'll see the sealer through the glass and will be able to tell if you have the glass uneven, or it's not sealed somewhere. Smear any extruded sealer on the inside to form a nice finish. CAREFUL. When smearing in this manner take care of the glass edge which may be sharp. Ideally you can cover this sharp edge with sealer.

Leave it for a half hour to skin, then fit your "L" shaped bits and screw them into position. You may want to apply a little sealer to these pieces along the inside of the recess, but it's not important. Like a cylinder head on a car, screw them evenly, a bit here, a bit there. DON'T screw one up all at once, fit them and work around each one bit by bit. Common sense should tell you when all is right, so I won't pursue the matter, but your care here could mean success or failure.

The screw holes you made in the front panel will have to be filled, and once done the front can be clad with self adhesive contact fabric as used for kitchen shelves and such, but in my case I used rippled hardboard which gave a brilliant appearance once varnished. Your own imagination comes in here - tiles, shells, you name it, just make it so good that your mates will gasp with envy. You can also create a picture frame look by fitting ornate picture framing around the viewing area and outside edges. Go for it, splash out a bit.

I'm going off the subject, but mine was in my shop. I had two hundred plus tiger barbs in it, nothing else, apart from the old 14" plecostomus and a few corys. Customers would come in and stand gasping and spend all day looking at my tank, many leaving hours later having not bought a thing. But this was good business, they always returned spending big. The sight of 200 TB's schooling in a tank this size with this magnitude of depth is a sight you never forget. I was offered 500 pounds sterling for the tank (1960s) big money then, but I refused. (Now where's all those bits of wood I had?).

To continue...

Hold on you guys, you can't leave the inside like that. All flooring has been treated in some form or other, so it has to be sealed, and after spending a fortune trying to find the right stuff I arrived at this. Your country may have different names for different products, so just shop around and you'll find the right product. I used a product called "Pondseal", and it's used for sealing the inside of outside concrete fishponds. It's non toxic, doesn't grow fungus hairs, which many of my earlier tries did, and it's available from your aquarium shop or pond dealer, hopefully. Once dried, it forms a hardish skin of rubber-like substance over the area it is applied to. I gave mine two coats, leaving two days in between each coat. Make sure the top edges of your boards are fully sealed, this is important. The stuff I used was called "Aqua Blue" and gave a great appearance to the inside of the tank. Ensure EVERY nook and cranny is completely sealed, even the unseen areas around the "L" shaped bits.

Problems
Well, not counting the 2 cwt. of gravel to fill the base, only one really, and that was planting. I had to don my wetsuit, mask, and snorkel to do it. Ha Ha. Seriously, planting was awkward, till I made up a grab arm that gently placed the plants where I needed them. You DEFINITELY need a Plecostomus or something similar. Mine was 14" long and kept the glass and sides sparkling. Never once did I have to clean the glass in five years. Think of the area, and make your fish work. Some for the sides and flat surfaces, rocks and things, others for the plants, more for the gravel and bottom, and others for the top. Paint a living dream of a tank.

Heating… WOW… Power bills. I used three 250 watt heaters with their own stats, as I learned early in life not to rely on one heater or one thermostat. Also one heater works harder and longer to maintain temp. than three, plus if one fails you don't lose your mates, and you get a better distribution of heat, i.e., no cold spots, no white spots, ha ha. Place the heaters as low as possible, but not touching the gravel. Heat rises, and placing heaters high in a tank causes cold spots, no matter how much air you have flowing from your filters and airstones.

One of the major causes of white spot is….. Geez… That's another story. Get your A into G Bill, concentrate.

The tank was fitted with an U/G filtration system of my own design, and had a 250 gal/hour circulation system that sprayed the return water over the surface. The fish loved it, and I can't ever remember losing one. Algae was no problem, my Pleco saw to that, and the interior never deteriorated or harmed the fish in any way.

Plants, I can't remember them all, but it was so dense I had Myriophyllum and Cabomba, Aponogetons, Amazons, Vallis, Madagascar Lace, growing over six foot long, in just a short time, and I used to spend more time "gardening" my tank than anything, as plants grew so fast I could hardly keep up. (Excellent for the shop sales though). Pygmy Chain Swords would shoot the length of the tank in just a few days, along with Vallis and ferns. I awoke one morning to find the surface of the water covered in flowers from the Aponogetons, something I had never seen before. Lighting was two four foot Growlux.

Brilliant stuff. Dream about it, Think about it, Make it happen.