I am new to this website, am hoping someone out there can give us some advice. We had our inground pool replastered 3 summers ago, and we have had nothing but problems. We followed the post plastering instructions to a tee, and have a professional company maintain the balance. It is a 20x40 white plaster pool, did a complete resurface and retile three summers ago. First summer of use (summer after replaster), there were little "bumps" popping up on the bottom of the shallow end. Since then, the bumps are spreading, and several have "exploded" (plaster floats to surface, looks like potato chips).
We have had the construction company out here several times. They have started to wet sand some of the bumps, but the problem keeps happening. They have no real answer as to why, it seems to be a different story each time. First they blamed it on our service company and said it looked like salt was dumped straight into the pool. Then they said it could have been a bad batch of plaster, something about the ratio of sand?
I've attached a few pictures to see if anyone knows why this is happening or how it can be fixed. We went with a very reputable company (Wilcoxon in Maryland), spent almost $20K on the job, and worry that we will have to replaster in a few years. I have attached a few pictures we took at night, when it is easier to see the problem. Any advice would be appreciated.