But if it DOES leak, there is a good chance the tank is ruined. And that's highly likely. I had a heck of a time getting my tank perfectly sealed and was thinking the whole time how much this would suck if the tank was plywood. Basically, very to no room for error when dealing with plywood.
I see people fixing their leaking plywood tanks buy just resealing, it makes you wonder what the integrity of that wood is now after water pushed through it. Its seems to me, that whole leaked through area is a future leak waiting to happen. And very rare is the DIY build that never has a leak at all.
I spent months trying to find the leak when I built mine.. the same for other larger builds.. (nolapete comes to mind).. I couldn't see plywood surviving the trial and error and all that pressurized water going through the wood and having much integrity left. I never did find my leak.. I don't even think it was a pin hole.. you can see pin holes. whatever it was was invisible. it was just several arbitrary coating that eventually solved the problem.
Its just an achillies heel that can be avoided.
I think what stempy is getting at is about building it right, right off the bat. You seem to be bashing plywood tanks based on repair capabilities, which is sort of a different animal. Yup, a glass or acrylic tank should be more repairable than a plywood tank because the two materials don't absorb water. Glass or acrylic aren't immune to issues if not built perfectly, your months of searching for a leak is a good example.
It would be interesting to be able to compare plywood builds that had issues down the line vs those that didn't to see if they could be categorized into builder sloppiness (improper epoxy mix, too few coats, poor bracing, too thin of material, etc) vs a more correct build out. To some extent, any leak in any aquarium, short of being shot by a pellet gun or some other traumatic event, could be considered builder error... and unfortunately it only takes one "error" to cause a leak no matter what the material the tank is built of.
It would seem to me that one difference between plywood builds and glass or acrylic is that the sealing/waterproofing of the seams of glass and acrylic is essentially done between the panel edges while the sealing/waterproofing of a plywood tank is essentially an external seal (inside of the tank, but external in relation of the panel joints). I'd think it would be easier to get it right the first time with plywood, assuming one uses the correct materials and design, simply by putting enough coats on (then again, each person's definition of "enough" is different, and I suspect those who go with fewer coats might have more troubles) and allowing for proper curing before putting the tank under the stress of adding water.
I think stempy mentioned using 7 coats of epoxy. It would be curious to see how many builds going to that type of care, as opposed to taking shortcuts by using 2-3 coats, thin materials and such, are success stories or not.
