I started my build inspired by TheFishGuy's (TFG) thread in Cichlid-Forum "1122.08 GALLON TANK PROJECT!!!". I came across the thread in the DIY section and was amazed by the thought of building a fish aquarium using plywood. I first saw it when his thread was 35 pages. Now it's up to 123 pages!  I recommend checking it out if you ever plan to build a plywood aquarium for yourself. 

I was so inspired by his project, I decided to build a 75 gallon desktop tank, too.  Read on to see how I did it!

When someone says aquarium, 2 materials stick out my head: glass or acrylic.   Here was a man who had visions grander than most people.   His tank was initially going to be 1122 gallons and ended up being 800 gallons.  The weight of water is about 6,700 pounds - most people don't know that.  That is just about the weight of TWO Ford Explorers!  I was amazed and hoped for the best for his grand vision.

When I first read about his tank, I was starting www.txholeyrocks.com .   TFG's tank has been up and running since with only two problems.  One was a false leak and the other a leak in the bottom of the tank caused when he walked around to move some decorations around.  The leak in the bottom was remedied with re-coating the tank inside with another product called Sani-tred.

On an impulse I started this when I was at the hardware store and found 14" x 16” glass.   I purchased 2 glass pieces thinking I would do a small scale build.  I purchased a 4x8' sheet of 1/2" plywood cut into 4 pieces   I also picked up a portable jig saw, DRYLOK, paint brushes, screws, and silicone (type 1 GE).  This was the start of my project.

I was going to built this to go on the kitchen counter.   I would have enough space under a cabinet.  I was thinking it was going to be a 2 way view.  Then I decided instead to do the maximum size possible with the materials I bought.  It's ironic how that happened.  I quickly realized this wasn't going to fit where I intended it to be.

I proceeded to cut with the jig saw the sizes I needed as well as the 3 cut outs for the glass front.  I pre-drilled the holes because it's plywood and only 1/2” thickness.  I counter sunk the holes as well to ensure the screw heads would be flush.  I then proceeded to screw the back wall and the bottom on first.  After I had 4 holes drilled and screwed.  I then took it apart and applied wood glue.  I proceeded to screw in the 4 screws I had and found it difficult to find the holes I had drilled already.  It's difficult trying to hold 2 pieces of wood together to align holes that are pre-drilled.  I got that together and proceeded to drill holes every half inch apart trying to hit the center of the half inch and not pierce through the front or back of the  half inch plywood.

The sides were just as difficult and I did run in to a snag as to what side to screw first.  The back wall or the bottom.  I the bottom first and then screwed the side in to the back wall.  It did snug up, but not as tightly as I would have liked it.  Wood comes with natural warp so I struggled with this for a bit.  My seams are not the prettiest, but since this will get DRYLOK I figured it would fill any small gaps.  I repeated this for the other side.

The front piece had 3 cut outs for the glass.  I found I had to be really careful because I didn't have much wood to screw into.   I pre-drilled all the wood and then realized I forgot to glue the wood.  I had to unscrew the screws loose.  When I attempted to screw the front piece back  I couldn't align the holes again.   The glue was drying and well I had no choice other then to start over on my build.

I opted to take what I just had experienced and go with 3/4” plywood.  I decided that it would be much easier.  Since I was going with 3/4” plywood I would just go with a custom piece of glass instead of 3 small viewing pieces.  $20 for the glass to be cut using 3/16” thick glass 16" x 36”.  That would leave me with a viewable area of 15” tall.

I repeated the steps, but had greater flexibility with 3/4” than I had with 1/2”.  So much simpler to screw in with out piercing through the front or back.   Using 3/4” vs 1/2” was simpler.  I went with 1/2” because the cost was half that of 3/4” the first time around.

Applying the DRYLOK to the  plywood was interesting.  The consistency of drylok is like peanut butter. Not difficult at all, just a little different consistency over painting.  I did a pattern so I didn't miss an area.  Drylok takes 3 hours in between coats.  3 coats are applied to seal the plywood.   I did 2 coats and let that dry 3 days and then applied the 3rd.

On TFG's thread when he and I talked of ways to build a top he mentioned he wished he'd dryloked the outside as well.  That's due to the moisture on the top portion where condensation from the plastic was used made contact with the wood.  I kept that in mind and did an exterior coat as well.  I had to do the bottom edge and bottom in a 2 step process since it's not elevated on saw horses.

I waited for a week for that to dry and put a bead of silicone where the glass was going to be.  I put the glass in place and put weights on top of the glass.  I then put a bead all the way around the glass.   This sat to cure for 4 hours before I placed the aquarium on it's bottom.  It was basically finished other then applying  silicone to all the inside seams.  (I used white because I purchased the white by mistake.  On the front I think it was beneficial as I can see any area's on the front that got too much as well as able to see the areas I had air voids that needed to be loaded with more silicone.

I want to let you know Silicone is a messy product.   When it's drying it emits a byproduct called Ketone.   I used lots of paper towels to wipe it from my fingers.  I used my index finger to make sure the silicone was pressed firmly in to all the seams.   I used 2 tubes of silicone for my 75 gallon aquarium.

I recommend GE type 1 silicone.  Cure time is 5 to 7 days for this type of project.  The silicone beads are thicker under the glass portion so the normal times stated are not  DRYLOK according to TFG.  When I applied the front glass in I held off on applying silicone to the seams because the smell was very strong.

I plan on putting 1/2” round trim on the inside of the plywood where it meets the frame as I don't think it's appealing to look at the 90 degree sharp edge.  You can see some of the trim on the photos.

Overall I would recommend this to anyone who has some time to build a project like this.  It's not something that's very difficult, but patience is required.  It's a lot more time to build this then it would have taken me to complete an acrylic aquarium.  I won't be building a large plywood aquarium in the future.  

Please note, if your building a plywood aquarium on large scale you'll need to put cement hardipanel.  Cost effective of plywood aquariums over glass is cheaper if it's a large plywood aquarium.  I probably didn't save any money on this project if I went to purchase an aquarium.  It's the experience and satisfaction I was after.  Plus, I got to pick my dimensions.    To date I have built all my aquariums I have had using acrylic.  Late spring or summer I have plans to build an acrylic aquarium that will probably be 8ft  x 20” x 20” with 1/2" acrylic.  I will document that build as well, so check back in the future.   The aquarium will house many African Cichlids with choice TX Holey Rocks from my private reserve.

Zak White
Owner