it says on the lable that its fully uv stabilisedI wonder if there is a reason that preformed is green does it maybe aid in the biological workings of the pond .I saw on a swimming pool liners sight the reason they like blue liners is not just because it makes the pool look pretty but it aids in them adding stuff to the liner mix to aid in water conditions and the blue is a more desirable color .I wonder if the green there helps also .