Large Plywood Tank

EnglishAL, I was talking to a friend of mine who does acrylic construction and passed the idea about the 1/4" against the plywood to line the tank with and then a 1/2" piece for the front. His only concern was that you could have an issue with the 1/2" bonding to the 1/4" stuff properly. Oh the bond would be there but if you didn't have the plywood resting against the acrylic perfectly, then the seam could blow on you. Even the slightest space could cause enough pressure to make the seam blow.

That was his only worry. But I like the pond liner idea. Now the question is the seal using the acrylic front panel. Something to look into.

Cheers!!

Pat
 
Sean : EbN - Those are good suggestions. I'm no wood-worker, so I can't comment on #1. I was thinking about doing #2 (called filleting). It does greatly increase the strength (based on what I've read, 'cause I"m no composites expert either). #3 is a good way to put a layer of color on the outer layer of resin.

A couple of tried-n-true, save paints include:
1. Sweetwater epoxy paint, by Aquatic Ecosystems (www.aquaticeco.com)
2. Devoe Bar-Rust 233H epoxy paint. http://www.devoecoatings.com/index-working.html. You can use their "Service Locations" page to find a place near you that sells it. Here's the mini datasheet: http://www.devoecoatings.com/minidatasheets/233H.pdf. This is what I was planning on using before Mastino Mike brought up the pond liner thing. A pond liner isn't going to crack if it flexes a little bit. Plus it's cheaper.

ChrisB - As for you question about epoxy paint: You don't need to add any pigments to the paint. You can just get whatever color you want that they make. I mentioned adding pigment to epoxy resin, because the resin is basically clear. It does affect the properties of the resin a little bit though, so pigment should only be added to the last 1-2 coats.

-Tom
 
Called about the 233H epoxy paint. $64 gallon. No idea how much it might take. Dimensions likely to be 8x4x2. Anyone have an idea?

Tom -Where would you go to get the resin for "filleting"? Would you just ask for epoxy resin? The resin in the seams sounds better to me than using fiberglass.
The resin would go on before the paint, right?
 
This is another approach to building tank you can consider.

wood frames with plywood sides,bottom, glass front/sides. Sealed with silicone and waterproof 0.06 inch thick white plastic paneling.

description of the general methodology- though sides of the all but the 100 are done with frames instead of stacking 2 x 4
http://homepage.mac.com/nematode/IMAGES/100gTDIY.html

a 29 gallon built from oak 30x17x 21 h
29.jpg


still running strong.

a 100 g from pine 72 x 27 x 17 h
100tanksetup.jpg

also seen behind 250 picture below, and below 260. developed very small leak after two years. I think it was from twisiting when I lowered it to below the 260 with sand in in and it twisted and creaked a lot during the move.

a 250 from pine 50 x 48 x 30 h

250sm.jpg


250tanksm.jpg

taken down after six month cause it was an poor shape- too deep,

a 260 from pine 96 x 36 x 21 h
(5/16 inch glass)

500sysbasesm.jpg

Running great - this is an old picture before I removed the 100 from below in august

personally, I think this is much more likely to last long term than a liner system if you have urchins etc.

I'm certainly not sure it is as sturdy as a well-done epoxy paint or fiberglass sealing job, but it sure is a lot easier and a lot less smelly/messy.
 
ChrisB - The liner is definitely cheaper than the expoxy paint and resin! The cheapest places I found epoxy resin online are at www.tapplastics.com and www.mrfiberglass.com. To make the resin thick for filleting, you get a filler. TAP Plastics has Cabosil and the other place has something like it. Add filler to make the resin thick enough. Then you can put it in the seam and smooth it out with a stir stick or something. Be sure to watch your pot life, so get something that cures slowly or be fast!

Nematode - That's a cool idea too. That's a really cheap way of sealing the inside. The seams would still concern me though. That's the weakest part anyway. Perhaps a combination of methods would be best.

For example, you could use the plastic sheet to seal the sides. Then get just enough epoxy resin and some filler to put a fillet along all the inside seams. That way you don't have to buy $100+ worth of resin to seal the flat sides, but you get the strength of the epoxy in the weakest parts. That'd probably be cheaper than a pond liner too, and perhaps more resistant to urchins.

Maybe an even better combination would be to use the plastic sheet for the sides and then a strip of pond liner material along the seams. That would have the flexibility of the liner at the seams where it would matter.

I don't know....Any other thoughts?

-Tom
 
Wonder how UV resistant the plastic sheets are. I know some plastic breaks down and becomes very brittle after long term exposure to sunlight.
If it is highly UV resistant, I will probably lean toward using the resin AND pondliner on the seams, then use the plastic for the sides.
 
There are some pond liners that are not that flexible at all and uv resistant and are more like plastic that you could layer the sides of a tank with.
 
Tomason, are you the Tomason from AF? If so have you talked to KeoDog about his 300 gallon plywood tank? If none of this makes sense... sorry for the intrusion.
 
tazmacd
I think you may be right about the need for a very good fit of the inner acrylic box to the outer plywood box. My concern had been the problem of sealing the glass front to the acrylic sides. I know that silicone will not stick to acrylic.
I have sent an enquiry to the company in England that Mastino Mike posted. I figured that I would cut an opening in the front panel of the box liner to match the front frame and then seal the glass against the strip of liner that remains. With this method the pressure of the water would "force" the liner into a sort of gasket between the glass and the plywood (or in my case stainless steel) front frame (plus silicone of course).
I am still worried about boring critters and from what I have read in this post no one seems too concerned.
Alan
 
jfinch - yeah I am! I didn't know he had one.....I'll PM him today and maybe talk to him at the meeting tonight.

EnglishAl - I was thinking about doing the same thing with a fitted liner. I asked Pearls of Paradise about their fitted liners and what I should use to attach the panel with, and they mailed out a sample to me yesterday for me to try some things with. I'll let you know how it works. I've got weldon 16, silicone, acrylic, and glass, so I can try a couple combinations at least.

-Tom
 
Here some food for thought. The attatchment of the liner against the acrylic or glass does not have any tension on it so it doesnt have to be super super strong. You are just trying to create a water tight seal and the liner will be held in place by water pressure.(you create a lip or attatchment on the inside of the glass or acrylic behind the front frame of the tank). Im not worried about any critters burrowing through the liner because Im just doing fish but for you reefers maybe it is a major concern depending on livestock choices?
 
Footnote
I'm still not too happy with a liner that some critters can bore through. I've not seen any comments in this thread. I will start separate thread - maybe that will elicit replies from others with experience.
Alan
 
EnglishAl,
That looks good and might work great if you use enough silicone but I have my acrylic up against the plywood and liner on the inside of the acrylic. That way you have the liner and the silcione forming a seal. If the glass or acrylic bows then you might have a problem with you seal
 
Mastini Mike
I'm not sure what you're saying - I thought my drawing showed the glass sealed to the liner with silicone.
Alan
 
Your drawing has the liner on the outside of the glass, sealed to the glass and the outside frame. I believe Mastino is talking about having the liner be the innermost layer sealed to the glass only. That is the way I was thinking of doing it myself anyway.

I am also concerned about creatures chewing thru the liner. My head is spinning over this. At this rate, I will have a dozen layers of crap before Im done. :)
 
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