I guess I'm just saying that I wouldn't throw out a blanket statement of how unnecessary it is to factor in a safety envelope when the reality is that the opposite is true. Considering the ratio of failures that we see, even from the folks willing to share their debacles here online, a safety margin isn't unnecessary.
Even your own build factored in over building.. you didn't need to put in a fiberglass shell or use the ratios that you did in your mixes. But it made sense to you.
Nice build though, by the way.
Some people can't do their own taxes or have difficulties changing light bulbs. These people need all the advantages to their side as they can get if they decide to try to build something, especially when that something is inherently pushing the limits on material physics.
Even the stacked lumber build, I would admit that it is wasteful if someone used it that had the skills to do otherwise. Though on the original build by Pete, I don't think it was wasteful considering the depth that he was trying to achieve. Some of these others that are only around 2 feet deep, maybe not. But who's to say that the tank won't last decades longer?
Each builder needs to analyse their own skills and weigh that against how much safety envelope they think they need and the cost involved.
I can climb on my tank, get in it w/e with zero fear of causing microfractures in the epoxy that would eventually leak!
