G Pearce wrote:
I forgot the material name of the liner used in extreme cold conditions.

I also recall there was a formula for calculating the size of the liner
depending on length, width and depth of your pond.

I want to make my pond deeper so I am just going to cut the bottom of the
existing liner so I can keep on digging and then just put the new liner on
top of the remaining old one. If anybody has a better way of doing this
then I would really appreciate the expert advice.

Well, I don't think of myself as an expert, but my answer to your questions
are EPDM for liner up here in Canada. it is more flexible and won't crack in
the cold we get - mine is ~15 yrs old and no problems yet - PVC is being
replaced around here in under 5 yrs and haven't heard of anyone around here
with Permalon - also not flexible, I've been told. We have to deal with
frost in the ground and movement it causes
and...
Length (at the longest point) +1' for trimming plus twice the depth will
give you the length of the liner you need and..
Width (at widest point) + 1' for trimming plus twice the depth(at deepest
point) will give you the width of liner needed
i.e. L + Dx2 + 1' = lenght in feet & W + Dx2 +1= width in feet
The reason for the " X2 " is you have to go down one side and up the other
Gale :~)

Thank you very much !!!

This was my first pond and yes I made the mistake of buying one of those
Beckett ponds kits that use PVC liners. Less than 5 years old and I
believe there is a small hole somewhere near the top of the pond as I
lose water up until that level , no matter how much I refill.