Hello everyone, as many of you may have heard of or seen a plywood aquarium and wondering how to build one, you're reading the right thread. I will answer any and all questions and respond to all opinions and this thread is posted on Reef Tank, Reef Central, and 3Reef. I have been in the process of constructing a plywood aqaurium that is going to be eventually a reef tank. Now first of all there are many different ways to build a plywood tank but I'm going to share the things I did so you can get some ideas to go off of as the materials everyone is available to varies. I'll start answering some questions some of you may have: WHY BUILD ONE? I currently have a 90 gallon reef tank made by Oceanic a long time ago. I believe the tank is pushing 10 years old and I've had it for 5 with the 1st year it being a cichlid tank and then the past 4 years being a reef. I've always had a passion for fish in general and especially saltwater fish. Unfortunately, saltwater fish get quite large and espcially in a reef aquarium the selection of fish is limited and you can't keep as many as a typical freshwater or fish only tank. So having only 5 fish in my tank (flame angel, squamipinnis anthias, blue hippo tang, desjardini sailfin tang, yellow tang, and a marine betta) kinda disappointed me. At times the tank looks empty but with adding more fish the whole ecosystem could crash so then I had the crazy idea of buying a bigger tank of about 300 gallons and reef ready (pre-drilled). I quickly found out that option was not in my budget and quite expensive as the cost was easily a few thousand for just the tank and stand. Being creative and a little stubborn I wouldn't take no for an answer so I stumbled upon a plywood aquarium on the internet made by King of DIY on YouTube. I was interested in the idea so I gave it a shot because building a plywood tank is challenging but in the long run cheaper than buying an all glass tank. In reality, most people only look at a fish tank through the front panel and maybe the sides so I figured why have glass all around the tank when I'm not even going to see through all the parts? So I decided to have plywood on the sides I didn't want to see through which was for me the back. THE FIRST STEP? Many people have different methods of building a plywood tank such as to build the tank or stand first. I have seen lots of cases where the plywood "box" was built first then the stand but I thought that would be not logical because once the glass would be put on it would be extremely heavy to carry and also it would just be sitting on the ground. I didn't like that so I build the stand first because I had a fixed space in which to have the aquarium and the stand should slightly be bigger than the tank so that's the route I took. Stand first then tank second. WATERPROOFING THE TANK? Many people want to make a plywood tank but are confused on what to use to make the plywood waterproof and be strong enough to hold water. To waterproof my build I used a two part epoxy called Pond Shield which was almost $300 for 1.5 gallons which was more than I needed to cover all the wood. The rule of thumb was to have a 40 mils thickness of epoxy to achieve waterproof properties which meant numerous coats. Pond Shield has very specific instructions on how to use their product but the pros of it are that it has almost no odor, easy to appply (I recommended with rollers and brushes for seams), mix, and can go on a variety of material from wood to metal. The first coat was very thin because the wood absorbed the epoxy so then i added a little heavier coat 24 hours after it so it cured and dried. Then on the third coat I applied fiberglass over all the seams and epoxied below and on top of it so it stuck and gave more structural support. I added 3 more coats after that for a total of 6 coats which is about the amount needed to have 40 mils thickness. I'll answer more questions such as the filtration, glass, overflow box, glass, braces, and anything else you guys are interested in. Remember, this thread is on The Reef Tank, Reef Central, and 3Reef to get it out to more people. If you are going to start a build you can message me if needed and as I like to say, Happy reefing to all, and to all a goodnight!