On 6 July, 16:39, wrote:
OTOH, the foam underlay that goes under the carpet is fantastic. It is li
ght as a
feather, can easily be torn or cut to fit into shape and a little duct ta
pe holds it.
After a few years it was still "springy" underfoot. Have spent anytime
in the pond
lately (having learned my lesson). It is well worth it to get NEW foam
underlay,
carpet places may have ends or pieces cheap, because old foam may have st
aples and it
just isnt worth it to lay that expensive liner only to have it spring a l
eak.

Foam underlying sounds like a good idea. On mine, I'm still going to
put sand on the base because it is very uneven and I can use the sand
to even it out more easily. But underlying on the sides should be
simple. There's even a carpet shop near me that puts (new) offcuts of
underlay in a skip outside their shop so I might be doing a bit of
skip diving soon.

Matt