I'm wondering if they were referring to fiberglass and overall strength. I have seen other references to fiberglassing the outside of a joint or board providing more strength than on the inside. In either case you'd need to epoxy the interior for waterproofing and it is my suspicion that a fiberglass layer or two would be the most reliable way of avoiding micro-cracks allowing water to get to the wood.
950 Plywood/Acrylic Build on Wheels!
- Thread starter FisheadFrank
- Start date
I'm wondering if they were referring to fiberglass and overall strength. I have seen other references to fiberglassing the outside of a joint or board providing more strength than on the inside. In either case you'd need to epoxy the interior for waterproofing and it is my suspicion that a fiberglass layer or two would be the most reliable way of avoiding micro-cracks allowing water to get to the wood.
They said that the fiberglass causes some type of chemical reaction (can't remember the term) which is why they said to fiberglass the outside seams for strength rather than the inside of the tank. Polymer Composites has a build on youtube showing how they built a plywood tank using that method.
Not sure how you'd get to the outside seams 
I can tell you mines been running literally issue free for 5 years with the inside seams fiberglassed using max acr. I would not take that advice of skipping the inside fiberglass If I were you...
I can tell you mines been running literally issue free for 5 years with the inside seams fiberglassed using max acr. I would not take that advice of skipping the inside fiberglass If I were you...
I will be fiberglassing the inside as there is no way with the supports on this tank that I will be able to fiberglass the outside. I was just passing on what they said and found it interesting.Not sure how you'd get to the outside seams
So a little off subject but ,, what type of fish will this tank be used for? In my opinion its risky, but your money, your house, your life,, live it!
After about 7 Coats of Max ACR, we did a test fill. The tank leaked around the 24" mark on the left bottom side of the tank. 
You are rushing things it seems. Let everything sit and cure properly, especially the fiberglass. How many layers of fiberglass did you use on the seams? Was the leak around the window, as it should have been pulled so that the whole tank could be sealed then the window sealed up against the epoxy.
