I am just starting my 465 gallon raised wooden pond project with a 5 foot viewing window, it will be 8 x 4 feet, my question is, after some reading is that I would like to buy a 1mm butyl pond liner which I believe is the best, ( as I don't like to skimp lol) I know these are more expensive but are they worth the money or am I just going over the top for what I am trying to achieve ?