I'm in the process of shocking our pool using the BBB methods. This morning I was doing the prescribed brushing, and I'm noticing quite a few spots that don't brush up. They look exactly like a rusted nail head. Some in clusters, some along an obvious seam. Could it be that the vinyl liner is somehow nailed in place and the higher chlorine levels yesterday has damaged the heads?
Should I abort this shock process & revert back to a more traditional (less harmfull??) method of shocking?
How often does a liner typically need replacement, and how big an expense is it? What can I do pool care wise to extend the life of our current liner??