Curtis I'ld love to help ya,hell of a commute tho.Decks around here are going for $15 a sq foot. I just did 2 decks for a friend that where 16ft x10..done in 2 days,and all for a big fat thankyou..(working for friends sucks). I'ld think in a stock tank it would take some thinking. I like the border of rocks idea,then maybe a liner,like for outdoor ponds.That way ya get no bleed thru of finer dirt particles running into your water. Metal stock tank,maybe have someone weld in a *divider*,that way you could shape it to, like the shape of an *S*or somthing.