Building an Hexagonal Acrylic Aquarium





Introduction: Building an Hexagonal Acrylic Aquarium

Here's a fishtank I built to fit inside an old oak coffee table I found at a flea market. It's not a simple build, but I managed to figure it out mostly by myself with little prior experience. Here's how I did it.

Step 1: Materials and Tools

I started with the oak end table and some acrylic sheet from Home Depot.  The acrylic tube came from a plastics wholesale business. Have as much of the acrylic pre-cut as possible. When I need to cut acrylic, I use a jigsaw with a plastics blade.  You'll also need a propane torch and an acrylic solvent called methylene chloride.

Cutting a straight line along edges that will be watertight is really important. Cut and file edges smooth and you'll be rewarded with a tank that won't leak. I find it useful to build cardboard models of my tanks and then use them as templates for my acrylic.

Step 2: Bending Acrylic

 An acrylic hex tank is just 2 pieces of acrylic. One for the base and one long piece for the sides. This piece will have 5 bends and 1 seam.

Because the base is already cut to the exact size and shape for the tank, I will make each bend fit the base. Because the acrylic is flexible, exact precision is not required. Nonetheless, we want to make our bends as square as possible.

Clamp the acrylic so that the bend just overhangs the edge of the bench and heat it with a propane torch set to a medium flame. Keep the torch moving! You want to soften the acrylic but not melt it. If you see bubbles, or if a lick of flame is left behind when you move the torch, then you're getting the material too hot.

Once the bend forms, take the clamps off and set it on the base. You'll have a couple minutes to get the bend at just the right angle. Hold it for 3 or 5 minutes and it will cool and harden in place.

After it cools, mark the spot for the next bend with a Sharpie.

Step 3: More Bending

Keep bending, marking the next bend after the bend before it cools. The key is to keep the bends square so check the position carefully as you clamp the piece before each new bend.

Step 4: The Last Bend & Joining the Seam

On my bench at least, there's no room to make the last bend. I had success heating that line and then improvising the bend as best I could once it was placed on the base. Note the overlap in the second picture. We need to get rid of that next.

Clamp the tank to the base. The goal is to find an exact mark where the excess needs to be trimmed, both top and bottom. Use painter's tape on both sides of the acrylic to minimize chipping and cut. I tried to cut a bevel  edge that would hopefully mate with the bevel I'd previously cut on the other end. It worked pretty well considering the lack of precision involved.

Once the piece is cut, I tape it so that it fits the base. FIrst, a lot of tape on the outside while I applied thickened solvent into the seam. Then, turn it over and apply to the outside of the seam. This worked very well for me, I never had even a single drop leak.

Step 5: Attach the Base & Light Tube

It's time to attach the tank sides to the base using the acrylic solvent. I had precut a hole in the base piece with the jigsaw. I used the thickened solvent to fill the seam both top and bottom. The tube extends comfortably above the water line.

Step 6: Test With Water

 If your edges are smooth and your bends are square and your bonds are strong, it'll hold water for many years. I can't promise you success, but I've had great luck just taking my time and practicing on scrap pieces. My experience has been if it holds water for 24 hours, it'll hold water forever.

The light fixture is a 12" florescent fixture with an aquarium spectrum bulb. I built a little stand fro scrap acrylic to hold it up with reach. It lights the tank wonderfully.

Step 7: The Finished Aquarium

And here is the finished tank, ready to add fish.



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    16 Discussions

    not to be an @**, but i dont think theres enough gas exchange going on in this tank with the top of the table in place, if you look you can see the glass collesting moisture and fogging personal opinion.

    You could also use a "heat gun" to soften the acrylic (I'd recommend using one of the push-on ends that narrows the air stream to focus the heat where you need it better). Less chance of damaging the material than you have with a propane torch.

    i think it can be done with an LED light on top

     Can you tell me more about the "glue" or solvent stuff that holds it together? Where do you buy it, what's it called, etc.?

    1 reply

     Can you tell me more about the "glue" or solvent stuff that holds it together? Where do you buy it, what's it called, etc.?

      This is pretty cool. I have a 5 gallon hexagonal tank that I paid $40 for that has GREAT reviews and it works great. I love it. Even though I enjoy making things, it seems like a lot less time and cheaper to pay the $40, but that's just my opinion.

     I really do like it though. I don't have all the tools to make something like this, but I have this large end table sitting next to me that is hexagonal and probably 20 gallons if it were a tank. How cool would that be?!?!

     I belive fish (and perhaps other aquatic animals as well, not sure) need to get the light from straight above in order to get a good sense of orientation and well being. Like stinna2 already commented, the lack of filtration will make this aquarium unhealthy in a short time. The plants will provide oxygen, but the water still needs to be stirred or else there will be a layer of proteins and other dirt on th surface.
    Apart from that, the tank looks really good! Maybe you could keep snails or shrimps in it, that way you wouldn't need to worry about the size of it being to small for the fish. but some guppys would prbably do just fine in there too.
    Good luck!

    3 replies

    The tank has an undergravel filter. I cut a couple up and glued them back together to make a filter plate that covers almost all the bottom. If you look closely in the picture above, you'll see the air tube on the opposite side of the light tube. The air hose goes down the light tube.

    I really don't think the fish care where the light is coming from.

    Oh, sorry about that. Sounds great.
    I really don't wanna come off as a "miss-know-it-all", but i'm pretty sure that my statement about the lighting is atleast somewhat accurate. in nature, the sun is always above the water, shining down. Most fish are coloured so that their underside is lighter (to blend with the light from above) than their oversides (to blend with the darknes from below). Plants should probably benefit most from aboveside lighting as well, or else they may become crooked. But your plants look relly godd and healthy, so maybe i'm wrong about that one.
    Anyhow, I really don't hink that it's VITAL for the fishies survival or anything. :)
    I have lights on the side of one of my tanks as well.
    I think we have the same fish...platys?

    No problems. I don't claim to be an expert on fish (or anything else really). I need to add a bunch more details to this instructable and will in the next day or two.

    i just noticed your build.  Very nice!!  i am just wondering about filtration...

    DON'T OPEN THE DOOR!!!!!!! AHHHHHHH!!!!!!!!!! JK, It's enclosed. You can open the door. =D

    Cool!!! You might want to put some comments in the photos in step 4 to make the process a little clearer. Otherwise great Instructable.