Plywood Tank Build 300 Gallon

[andy8383]

Hi All,

After looking through a number of threads on people who have built plywood tanks, I've decided to jump in and give it a shot. I've started to build a 300 gallon plywood tank (8' long, 2.5' tall, 2' deep) with an overflow stretching across the back of the tank. I plan to fiberglass the entire tank and install 1/2" sapphire glass in the front. The tank will be part of a non-profit office redesign I'm spearheading.

I have some experience (used to have a 75 gallon saltwater tank in college), but I have been out of it for a number of years. I know I'm going to need a lot of advice along the way, so I hope more experienced forum users can help give me some direction.

A few quick questions...

- After looking at the various waterproofing options, I've decided to fiberglass the tank (inside and outside - might be a bit overbuilt, but I want this tank to last). I've just started researching the fiberglassing process and it doesn't sound too complicated, but I have zero experience in this. Has anyone fiberglassed a tank before? Any suggestions on type of resin/hardener or where to get them? Any other tips would be very appreciated!

I've attached a few pictures to this post of the plywood being cut and screwed together. It's starting to take shape!

Thanks Everyone!

[sphelps]

The plywood part looks good so far. I've done some fiberglass stuff before but not a tank. I would guess it's not going to be all that easy to coat the inside of that tank properly nor will it be very cheap. Fiberglass resin is also pretty toxic stuff and don't forget you'll still have to coat the finished fiberglass with some kind of epoxy paint as it can rot. I considered something similar myself at one point but adding up costs pretty much exceeding the cost of glass so it didn't make much sense to me.

You might also want to consider 15mm starphire front rather than 12mm. Personally I think using 12mm will be a mistake as it will have a noticeable bulge. Even a standard 6ft 230 gallon uses 12mm standard and it's pretty noticeable, going up to 8 feet and softer glass will be much worse.

[Cal_stir]

I will be following as I am planning a build as well, seems that most use West, MAS, or US composites epoxy, some put a final coat of potable epoxy paint while others don't.

[mike31154]

I know a bit about the fiberglass & epoxy process having built a cedar strip canoe. No clue about plywood tank construction though. The glass epoxy process is indeed not that difficult, but you need a well ventilated area to work in and be prepared to spend a few $$$s on the premium epoxy resin you will need. There are different weights of cloth available, not sure what would be appropriate for a plywood fish tank, but if weight is not an issue, the heavier cloth will add strength.

Various boat building forums & vendors of kits/plans will be a great source of information. My canoe is built from plans produced by Bear Mountain Boats. There's plenty of info there on glassing etc. Along with the plans for the boat I also purchased the book Canoe Craft which provided plenty of guidance with regard to fiberglass/epoxy construction. The epoxy resin I used is the one recommended by many boat builders, the West System. It is pricey but the finish is excellent. With a fish tank you may not be that concerned with the finish on the resin since it will be covered? Hope this helps.

[Cal_stir]

what thickness plywood are you using and are you gluing and screwing?

[Aquattro]

Check Marc's old thread on his 1000g plywood tank, he might have a few tidbits to offer

http://www.canreef.com/vbulletin/showthread.php?t=31113

[andy8383]

Plywood is 3/4" inch oak. When attaching the pieces of wood together, we glue first and then screw them together. We are going to fiberglass the entire piece as well, but haven't yet.

And thanks for the link to Marc's thread. Already checked it out during the planning stages. Great build and very helpful.

[spit.fire]

Pond liner is cheaper but harder to seal, might wanna look into it

[gregzz4]

My neighbor built a freshwater stingray tank with a pond liner and is now trying to build another as his leaks bad ....

[andy8383]

So quick update...

Just after I built my 300 gallon aquarium out of plywood (still haven't fiber-glassed it yet or order glass), I was offered a 300 gallon acrylic tank with an established setup (skimmer, pumps, reverse osmosis, chiller, lighting, etc.) and an assortment of 10 year old, beautiful coral for $1,500. Everything is in good condition. Tank is 8 years old, but no leaks or noticeable scratches.

I think it's a great deal, but I'm worried about transporting the tank (It's about 1.5 hours away) and not killing all the coral in the process. While I was able to successfully keep fish alive when I had a 75 gallon tank in college, it's been a few years.

Any tips for moving or ideas for the coral? Definitely need some advice. Maybe it's not worth it? Any horror stories taking over someone's existing system?

And just for sake of conversation, I was about to purchase all my fiberglass/epoxy last week. Below is my breakdown. If I still decided to do the plywood tank, do you think this would cut it...

1 Gallon Black Sweetwater Epoxy Paint for final coat: $78.00 (http://www.aquaticeco.com/subcategor...Paint-1-Gallon) — planned to apply 2 coats after after fiberglass & 3 coats of epoxy
2 Gallons 635 Thin Epoxy & 3:1 Hardener (EPOX-635315): $128.00 (http://www.uscomposites.com/epoxy.html#epoxhard) — should be enough for 3 coats
1 Pint of Black Pigment (AC-BL032): $12.25 (http://www.uscomposites.com/pigments.html)
4" 50 yard roll for corners of 8.7oz Fiberglass Cloth Tape (FG-C04R): $27.60 (http://www.uscomposites.com/cloth.html) — for corners
15 yards of 7.5 oz Fiberglass (FG-C0750): $94.40 (http://www.uscomposites.com/cloth.html) — for rest of the tank

THANKS everyone for your responses so far!!! Definitely helped!