I was thinking silicone or melting plastic to repair the holes and cracks please let me know of any suggestions. Thanks!
Depending on whether the pond is a fairly simple shape, you might try covering it with a butyl liner and just considering the preformed plastic as a base for this. Butyl will last for many years if you get good quality. Otherwise I'd go to a water garden store and ask for advice on sealants, but this might depend on how bad the damage was - it sounds from your description as if there's quite a lot of problems. Maybe you need to remove the preformed plastic and start again. If you don't get a good liner in place, you will undoubtedly get more problems in the near future and will disturb all your plants and wildlife when you have to fix it again.
The bad part of preformed ponds, is once they crack, they cannot be repaired, no matter what. Sorry.
Come now ladies, haven't you heard about duct tape. RScott
