Plywood / Fiberglass Tanks

[TerryC.]

I am considering building a plywood fiberglass fish holding / growing tank. I know aquariums can be made this way. Other then the possible weight, is there any pit falls using a this type of tank?

TC

[jackalope]

I can't think of any pitfalls, as long as it holds water, the sky's the limit. I have an old hydroponics book that advocates using 2x6's for the sides of a grow-bed, 4x8 sheets of plywood split in half (2x8) for the bottoms, and plain old 6 mil plastic sheeting for the waterproofing .... true, you have to change the sheeting every so often, but it could be a whole lot cheaper than some of the grow-beds that are advertised, and it might also work fine for fish tanks too.

[TerryC.]

Great. I was looking at what others have done with barrels, IBC tanks, rubbermaid stock tanks, etc. and they all seem to work well however, I know me. I will never be satisfied unless I have the capability to go bigger if I choose to do so. The cost and transport of large tanks is prohibited. I have never worked with fiber glass but I have a friend that does.

I like DIY projects as well so I figured I would start with a 4 x 4 x 3 tank. This would require 3 sheets of 3/4" plywood, some 2 x 4, screws, and of course marine grade fiberglass / resin. (FDA aproved) The materials would cost a little over $100.00 when finished. I also read that the better quality of plywood used, the easier it is to prep for fiberglass. A/b plywood would add to the cost but might be worth it. Less filler, sanding, etc.

I am not 100% sure this is what I want to go with but I am leaning in this direction. If I decide to do this build, I will post images, cost, problems, photo's etc.

[badflash]

Be sure to use marine plywood. Normal plywood won't stand up to the moisture.

[TerryC.]

Hi Ernie,
I thought about using a pond liner but decided against it. My thought is if I ever decide to expand the system, haveing a little experiance building a tank might help.

Hi Badflash,
I originally intended on using marine plywood however, I read on monster fish keepers it wasn't necessary. Outdoor and marine plywood are designed to withstand rot and delamination from moisture and high humidity. Although you can use a "c" grade exterior plywood, filling all the knots and other discrepancies requires allot of work.

I have never worked with fiberglass but looking at how others are doing it doesn't appear to be difficult. I will be seeing my friend that works with fiberglass this weekend. I am trying to figure out why, once the frame is made and the plywood is cut to fit, they don't fiberglass the plywood first, (on a saw horse) assemble or attach it to the frame, and then fiberglass the corners and over any screws. I would think this would be simpler but there may be a reason it is not done in this manner.

I am still not 100% sure this is the way I want to go. I will more then likely start the build this winter so I have allot more time to do the reasearch and decide.

I am trying to decide if this guy has to much time on his hands. http://www.youtube.com/watch?v=CU9x_W9X ... re=related (http://www.youtube.com/watch?v=CU9x_W9X-tM&feature=related) Regardless, it's a nice system

[badflash]

Exterior probably will work. Interior comes apart. Good luck! Keep us posted.

[TerryC.]

"Do you have any good links about how to apply fiberglass over plywood?" Not really. ...I did find out allot of different information on the two links below.

Years ago I lived in Granada Hills and had aquariums with some semi-rare (at the time) expensive chiclids in them. That was until the 1994 Northridge earthquake. The tanks fell and broke. What a mess. I do have some knowledge with fish and tanks so I am hoping that will help. Again, I am kicking around allot of ideas along with deciding what type of fish to stock. If I decide to go with catfish, the tank idea will remain the same but the dimensions would change. Tilapia should work fine with the dimensions I was considering. The solid waste removal is interesting and I will consider ways to mitigate it.

http://www.monsterfishkeepers.com/forums/
http://www.garf.org/index.shtml

[badflash]

Solid waste isn't much of a problem. Set up your sump with a sloping bottom and take suction at the low point. Your pump will move them to the growbeds where they can be put to good use.

If you can raise cichlids, you'll have no problem with tilapia. That is what they are, but bigger and easier. Just keep them warm. That is the only down side to them.

[TerryC.]

If you can raise cichlids, you'll have no problem with tilapia. That is what they are, but bigger and easier. Just keep them warm. That is the only down side to them.

In Southern California the weather is generally warm. In the winter we do get some cool days now and then (40's) and even snow believe it or not, but this is a seldom occurance and only happens about once every ten years.. Reading moster fish board it was suggested that plywood is a pretty good insulator as it does not transfer heat / cold very well. I should have no problem keeping the tank temp warm. Further, with the 2 x 4 outer frame, insulating it should be easy. If anything, I may need to cool it when we get those hot summer days.

A private lake called Corona is near by. They stock talapia and catfish this time of year and a hybrid trout during the winter months.

[mpugh5@aol.com]

[quote="badflash"]Solid waste isn't much of a problem. Set up your sump with a sloping bottom and take suction at the low point. Your pump will move them to the growbeds where they can be put to good use.

that is a good point that i will surely incorporate. my plans are to go with the epdm pond liner ,to eliminate the building with wood i plan to build right into the ground inside the green house. i'll use the big 2-3" 4x8' thick pink-blue insulation boards. when i dig the footer for the green house, which i plan to be only tamped stone, i will do the layout for the 5' wide 10' long 4' deep tank. the sides will be against the 8" block wall layed on the tamped stone foundation with the box being the support. it will be mortared. i have 6" block for the rest of the green house foundation. it is a metal hoop green house that i want to sit on top of three coarses of block above grade to give me more overhead room. green house size is 16'x30' . with the tank built into the ground the grow beds will be directly over the tank so the only pumping will be up. all the returns will be gravity.
it's all coming into focus. i bought a transit last week, i just can't wait to get started. 8-) i'm still looking for idea's and sloping the bottom of the tank is an excellent one. thanks

[jackalope]

I was planning to make a couple of plywood tanks, but I was put off by the costs of the fiberglassing and the epoxy paint ....... I'm just going to buy 100 gallon Rubbermaid Stock Tanks ($79.00 at Ace Hardware) and possibly plastic gutters for the riverbeds. I need to go the cheapest route possible. I've also got some other ideas, but first things first ;)

[TerryC.]

I was planning to make a couple of plywood tanks, but I was put off by the costs of the fiberglassing and the epoxy paint ....... I'm just going to buy 100 gallon Rubbermaid Stock Tanks ($79.00 at Ace Hardware) and possibly plastic gutters for the riverbeds. I need to go the cheapest route possible. I've also got some other ideas, but first things first ;)

I too am looking at the cost but I don't think it will be bad. The tank strength comes from the wooden structure not from the fiberglass / resin like in many other structure / application..

The resin is the water proofing and the cloth / hardner will mainly be used in the corners or to cover screws. Applying 2 to 3 coats of resin should be enough to water proof the tank and I wouldn't think that would take more then two quarts on a 4 x 4 x 3 tank. I didn't get a chance to talk to my friend yesturday but I will see him today and will ask what he thinks. Hopefully I may get a better idea of what is involved

http://www.westsystem.com/ss/how-to-use/

[jackalope]

I too am looking at the cost but I don't think it will be bad. The tank strength comes from the wooden structure not from the fiberglass / resin like in many other structure / application..

The resin is the water proofing and the cloth / hardner will mainly be used in the corners or to cover screws. Applying 2 to 3 coats of resin should be enough to water proof the tank and I wouldn't think that would take more then two quarts on a 4 x 4 x 3 tank. I didn't get a chance to talk to my friend yesturday but I will see him today and will ask what he thinks. Hopefully I may get a better idea of what is involved

http://www.westsystem.com/ss/how-to-use/
I was going to paint the inside and outside, the paint would flow into any hairline fractures in the fiberglass ..... hopefully .......

[badflash]

I'm wondering if any figerglass is needed. Looking that site over, it looks like the epoxy sealant is all that is needed for waterproofing. Maybe some figerglass tape in the seams. What do you think?

[TerryC.]

I'm wondering if any figerglass is needed. Looking that site over, it looks like the epoxy sealant is all that is needed for waterproofing. Maybe some figerglass tape in the seams. What do you think?

That is the conclusion I keep coming up with. Reinforce the corners, seems, and any exposed scews with fabric and resin for the rest. My friend said that a little over a quart of 105 will work. He knows this stuff pretty well. This is his plywood / fiberglass (hydrofoil) sail boat he built http://www.tc-pro.com/doug081809/_MG_0048_thumb.htm

The resin hardner ratio is 5:1 Looking at a local dealer of west epoxy, a quart is $36.00 and the hardener is $39.00 (which is enough to harden 2 quarts+) So your still looking at over a $100.00 for epoxy alone. Add in plywood and 2 x 4 you are now pushing the $200.00 mark for a 300 gal tank. I haven't priced the good plywood yet (a/b) but I would think a sheet wood be $25.00 + I may go price it today or tomorrow if I get a chance.

[TerryC.]

I too am looking at the cost but I don't think it will be bad. The tank strength comes from the wooden structure not from the fiberglass / resin like in many other structure / application..

The resin is the water proofing and the cloth / hardner will mainly be used in the corners or to cover screws. Applying 2 to 3 coats of resin should be enough to water proof the tank and I wouldn't think that would take more then two quarts on a 4 x 4 x 3 tank. I didn't get a chance to talk to my friend yesturday but I will see him today and will ask what he thinks. Hopefully I may get a better idea of what is involved

http://www.westsystem.com/ss/how-to-use/
I was going to paint the inside and outside, the paint would flow into any hairline fractures in the fiberglass ..... hopefully .......

I would think for the outside you could use thompsons water sealer or a like product. It wouldn't come in contact with the inside of the tank and would help if you had a water spill. If you had enough resin left over, you could use one or two coats if you wanted to. Something to think about.

[jackalope]

I would think for the outside you could use thompsons water sealer or a like product. It wouldn't come in contact with the inside of the tank and would help if you had a water spill. If you had enough resin left over, you could use one or two coats if you wanted to. Something to think about.

Yeah, but I've got a different plan now .... I think it will work better for me .... (about 450 gallons) .... I might have to break a few laws (of physics) first, but it's something I'm gonna try ;)

[TerryC.]

I would think for the outside you could use thompsons water sealer or a like product. It wouldn't come in contact with the inside of the tank and would help if you had a water spill. If you had enough resin left over, you could use one or two coats if you wanted to. Something to think about.

Yeah, but I've got a different plan now .... I think it will work better for me .... (about 450 gallons) .... I might have to break a few laws (of physics) first, but it's something I'm gonna try ;)

break a few laws (of physics) :shock: Oh do tell