replacement liner for an 18 x 18 steel frame pool

Most liners cannot be removed and replaced. So far I don't know of anyone that has been successful due to liner shrinkage or becoming brittle.

What kind of pool so we can help you pick out a new liner.

Kim:kim:
 
Just to give you a comparison, we had a mishap 5yrs ago with our pool. My better half knocked a stake in the pool that I carelessly placed on the top rail.
Stake.jpg

I weighed the options of patching the hole (a clean 1/2" hole) or replacing the liner. Decided to at least try the patch approach first (had nothing to lose trying). Did it EXACTLY as kimkats described (small then larger). It's been 5yrs, but alas, I'm going to have to do it again because it is beginning to leak again.
Pool Patch.jpg
First thing! You can see how clear the looks thanks to TFP! But, it's lifting a bit, so patch again. It has DEFINETLY been worth the cost of a good patch kit as opposed to a new liner. If this patch lasts as long as the first, I'm ahead financially.

Just wanted to say sometimes it's worth a shot as kimkats said. Good Luck :D