The last time I acid washed my pool was in 2009, The scale was really bad around the tile line and a lot had buildup between the pebbles. I remember the guy was concerned about acid washing my pebbletec he had asked me if I had ever done before, which I never did. He agreed to do it and when he was done it looked brand new. Ever since the tile line has remained scale free but it has built up on the floor, steps and spa between the pebbles, some areas have thicker patches of scale here and there. I recently had three different pool specialist come and look at my pool to consider acid washing , all three of them declined to do the job in fear of losing patches of pebbles. One of them recommended pouring acid directly into the spa he said to start with 2 gallons and said it may require a third, he said that over the course of the next 2 to 3 days to go out and scrub every 3 to 4 hours on occasion, he said it may not even require scrubbing sometimes! He said if it works on your spa it should work on the pool and that the pool would require 15 gallons of acid, and that is what he has done before and I should be able to do it myself.
Anyone have experience using this method on pebbletec?