galabar,
Glad you want to be a supporter. My stacked lumber method works as demonstrated by Rich's and John's (2) tanks and the fact that my tank does not flex when filled. There's tons of people who told me in no uncertain terms that I was stupid for doing the stacked lumber and that I should just go with the normal walls like everyone else. Do you think I regret for one minute not listening? When I saw Rich, one of a handful of people on MFK that I have the utmost respect for, adopt my method and John's builds show up here with it that was a huge affirmation.
I like the staked wood for it's structural stability. but not for it's ability to hold water. IMO if you where to sheath the entire inside of the tank you more than likely would not be having all this problem keeping the water in.