WP's 55gal to 270gal plywood tank conversion
1 The idea
A long time ago I read about large plywood tanks. Fools, I thought... wood and water? A couple of years back I started wondering about it some more, comparing a plywood tank to a commercial glass tank. The economics didn't add up, so I bought a 55gal tank and forgot about plywood. More recently, the idea surfaced again. Now I am less worried about the economic side of it, but thrilled with the idea of a large home-built tank, with lots of invisible plumbing, water change system, and a generous depth, to fit exactly into a place where a 100gal tank sits now.
I am no professional wood worker, and before attempting something like that, I wanted to first get some on-hand experience to reduce the risk of a major screw-up, like flooding my house with several hundred gallons of water. So I started looking at my neglected 55gal tank with it's lack of depth and figured the nice big front and back glass might work well in a larger plywood construction.
Sitting in the garage, it wouldn't have to be perfect, and if it catastrophically failed, the worst that could happen is a lot of water draining out of my garage door.
In this journal I am going to show pictures of what I did step by step and the results of it. I don't want to challenge your patience, and had no clear idea if it would work (still don't) and how long it was going to take to finish. So by now I am a few steps ahead, and some of the epoxy is already drying.
But this is how it started...
1 The idea (this post)
2 Planning and preparation (next post)
3 Smashing a perfectly fine tank and building a foundation
4 Plywood, screws, glue and sand paper
6 Glass & Silicone
7 Plumbing & Filtration
9 Moving it into place
10 Wet Day
13 Top Lessons learned
2 Planning and Preparation
The more careful planning is done upfront, the smoother everything will work in the end. Since I was not in a rush, I took several months to think about it, read other successful and unsuccessful projects on the web, measure things here and there, evaluate the space and create a very detailed plan with a computer. Here is the schematic of the setup, created in Visio:
Along with that, I created a plywood cut plan, which helped to minimize waste. Going back and forth between the schematic and the cut plan, I optimized the size for my future tank construction. Originally I wanted to keep the length of the tank to 48" to take advantage of the plywood sheet size, but that would have meant to cut the glass panels, and I figured some additional length to build filter compartments into the tank itself would be cool too. Basically I ended up with two tanks, each of them LxWxH 60x22x24", resulting in two stacked 135gal tanks.
My collection of woodworking tools is fairly basic... We will need a drill or two with a selection of drill bits, a circular saw, some clamps, measuring tape, and a square. I also own a table saw which isn't necessary, but comes in handy sometimes. I often jump on super cheap deals at Harbor Freight, and my collection now includes cheapo jig saw, finishing sander, and grinder/cutoff wheel. And a rotary tool for different purposes.
Financially, I don't think this will save a lot of money over buying an off the shelf glass tank, especially when counting the hours that go into the project. I don't count them, because this is a fun/spare time project for me. Plywood gives us flexibility with regards to the size and plumbing which gives it an advantage over store bought tanks. And if it holds without leaking, there will be a large confidence boost... hey, I made this! Of course that can go the other way too.
One thing to consider... if not in a hurry, expenses come gradually, which is easier to swallow than one big lump sum. I bought the Epoxy months ago, the plywood over time, usually it didn't cost more than $60 a pop. Having the glass was a large saving for me. 2x4's and wood glue are very cheap items, and over several months I looked for deals that helped me to keep all of this fairly inexpensive.
You can probably guess my thoughts on this;) Sounds like you are going about it the right way. I had a LOT of trials and a coule of errrors, but I'm SO glad I stuck it out. Let your imagination go wild, because that is your limitation. Feel free to pm if you think I could help with a question:)
Ultimate DIY FTW!
Thanks tusk, your awesome monstrosity build is definitely part of my inspiration. Don't hesitate to speak up if you see something go the wrong way. :wink:
3 Smashing a perfectly fine tank and building a foundation
Once the 55gal tank was emptied, the question became how to separate the glass panels. A razor blade and a lot of tooth floss are a good starting point. The first seam is the hardest, once it is unglued all the other seams are comparatively easy to separate.
After half an hour with the razor blade, my patience ran out and I grabbed a hammer. Since I didn't need the side panels, smashing them carefully sped up the process immensely. The bottom panel of this 55gal tank was tempered, and to compare some I took the hammer to it as well. I found that tempered glass is much, much harder to shatter, and once it broke, it broke into hundreds of little pieces as expected. They are still very sharp... ouch.
As a side note, it might seem a bit weird to cut up a nice 55gal tank, until you realize how expensive glass panels can be if you buy one or two. With applied economies of scale, buying a complete 55gal tank is cheaper than buying the separate glass panels!
The floor in my garage is angled towards the street, and curved towards the center. Not a good base for a large tank. Therefore, I decided to build a concrete base. Soon I realized that this wasn't as easy as it seems, but after a couple of layers it was all built up fairly straight and level.
I am planning to add another layer of fresh thinset just when lowering the plywood construction onto the base, to make sure it is well supported and level.
To keep energy costs reasonable, I removed the drywall and filled the space with insulation. This should help to keep the tank temperatures cozy during icy winter nights. The plywood should insulate a little bit, and I will cut a fitting piece of styrofoam insulation to cover the front glass. As you can see, I also painted the garage floor with epoxy paint. Very easy to do, and makes a big difference in appearance.
plywood tanks are awesome! my friend has a 500 gallon plywood tank and the thing is huge!
one concern that comes up is the glass, do you think the 55 gallon glass panels are enough to hold the extra weight?......also if ur 55 gallon was a standard 55 shouldn't all the panels be tempered?
w/ those dimensions i get a minimum thickness of 0.31" @ safety factor 2 for non-tempered and .10" @ safety factor 2 for tempered glass.
I forgot the size of my piece of glass, but it was atleast $200 for the hunk with polished edges. Not cheap.
Keep the pics a comming :)
To be honest, I haven't given much thought to whether the panels are thick enough. I figure additional depth of the tank does not add a lot of weight (and I am probably wrong about that), and the height and length of the glass panel won't change. Instead of small silicone seams, the whole panel will rest against a (hopefully square) plywood frame, which IMO should not add much or any stress.
I have some more pictures lined up, stay tuned. :smile:
if i remember correctly my friend paid $2000 for his glass.
I am building a plywood glass tank right now its 80% done. I purchased 1/2 starfire glass for my veiwing window dimensions of tank are 97 1/2" by 24" by 24" 240 gallons I believe. The glass is 95" by 23 1/2" the glass is 95" by 23 1/2" the glass cost me $320.00 with beveled polished edges. I used fiberglass resign and cloth to seal it then I painted it with sweetwater epoxy paint from aquatic eco systems one gallon came to $110.00 that including shipping. If you would like to see pics so u can get some ideas just let me know. gotta love DIY
Very cool. An awesome project indeed :)
Did you use the West System epoxy? Why do you use Sweetwater epoxy paint, as an additional seal for the epoxy? How did you deal with the fumes?
4 Plywood, screws, glue and sand paper
To build the box, I used 8x4ft 3/4" plywood panels. When it comes to plywood, there are many choices, from very cheap (~$25) to better quality (~40) to really expensive hardwood (~$55). The main drawback of the cheap boards is that they come with lots of imperfections that might need considerable time to fix, and can even negatively impact their strength. This usually surfaces when you cut the boards and spot gaps.
For front, bottom, and sides I went for the middle-of-the-road, better quality plywood from a lumber place, where they also helped me with some of the long cuts. There is nothing that can't be cut just as well with a circular saw at home, but it is definitely easier to have this done with a large industrial saw, especially if they only charge like 50 cents a cut.
For the back, I was going to join two sheets, but then decided to use a different approach. I bought four very cheap, thinner boards (0.45") and doubled them up, so the join runs vertically on the back and horizontally in the front. Gluing the 60x60 board together was quite an interesting experience. I used a door as the base, since my garage floor isn't straight. Then I collected all clamps, buckets, concrete bags, and water bottles to press it all together.
It turned out alright, but like I mentioned, with cheaper plywood you get a lot of imperfections, and it took a couple of hours with wood filler and sander to get it all nice and smooth.
I bought 2" drywall screws at the local hardware store, and I used a couple of 18oz bottles of Gorilla glue to keep it all together. One very inexpensive way to increase the structural strength and assure the weight of the water does not pop the glue seams is to add triangular pieces of wood, ripped 45 degrees from 2x2's. This is where the table saw comes in handy... I glued these strips to all inside corners.
I opted for an integrated filter (and stuff) compartment. This makes applying the epoxy much harder, but I went for it anyway.
Main reasons: I don't want to use a canister or HOB or any such external filter. With the tank sitting in a garage that is not insulated, I think external filters would aggravate temperature swings, I would need more wattage in Winter, and the tank would heat up faster in Summer. Plus, with the tank design as it is, I wouldn't really know where to place it. Internal filters in the tank look ugly, and are messy to clean. Thanks to plywood I just added some length to the tank for 3 compartments (see schematic in second post): One for the pump (as well as heater, overflow to lower tank, and fertilizer reservoirs), a second center compartment for filter sponges, and a third "dry" compartment for some equipment, micro fertilizer, maybe maintenance supplies.
Braceless tanks make maintenance much more fun, and no light is reflected by dirty glass braces. For the top tank, I used a steel angle to add the necessary stiffness to the plywood.
The bottom tank is mainly planned as a fancy water reservoir at this point. It will get a shorter metal angle, combined with a threaded rod that goes from the front to the back panel to prevent any bowing.
One of my main concerns about possible weak points is that the top tank is mainly floating in air. When full of water, this is going to be a lot of weight supported by the sides panels. To prevent the bottom from bowing and ripping the front glass out of it's silicone bed, I added a 2x4 in front, 2x6 in the center, and a 2x2 in the back (where it connects to the back panel). Hope it will hold! I might add some more support from the outside.
Here is another shot adding the 45deg strips:
For easier access and handling, I am keeping both tanks and the back panel separate while applying epoxy. When done, I will screw the back panel to the tanks and apply epoxy to all the joins. The 60x60 double plywood back panel is very heavy, and when combined with the tanks I need another person to move it around.
At this stage I -cough- started to sand everything really smooth. Sanding sponges are my favorite tool, even though I used a finishing sander for some of the larger areas. Well, almost ready for some epoxy!
looks verry nice, I know i need to start a thread and im working on it. Its going to be a diy thread. The thing is im building some acrylic tanks some opent top frameless glass tanks and the monster 240 gallon plywood glass tank. When these projects are all done i will have an all in one thread.
To answer your questions the reason I used the sweetwater epoxy paint is because when I started this project I diddnt know about west systems epoxy so I used fiberglass resign and cloth that I bought by the gallon at the auto parts store. It worked great but then I was worried about the resign poisning my plants and fish so I put 3 nice thick coats of the sweetwater epoxy over the fiberglass resign so all together the fiberglass resign is about 6 mm thick with another 4 mm of epoxy paint over that, guarenteed not to leak and verry strong
when you apply your epoxy if you buy it by the gallon I suggest only mixing up 1/3 at a time so its not setting up on you before you use it up it does stink so I opened the garage door turned on the exaust fan and used 3 other fans to blow the fumes away as I painted and I also suggest buying cheap brushes and dont try reusing them and wear rubber gloves.
Very nice build. The quality of it is top notch. I can't wait to see the direction this tank is going in.
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