Would like to hear from anyone with experience in sandblasting ,chlorinated rubber paint from a pool? I recently contracted to do this and was very surprised that it was so hard to remove, these 4-5 coats. Seemed as though it was molded to the pool. The job took 13 plus days with a two man crew. I used a 375 cfm comp. and had a 600 pound pot.Using black beauty, a1/4" nozzle and 110 psi. What did I do wrong? Thank You for your input ! P.S. the pool was 36'x18'x2-1o'.