Our pool was put in around 1988 I believe, we've only owned it for the last 4 years and you could see the blisters with surface cracks since we've been here - though they appear to have gotten worse over the last couple of years. I believe we've kept the water pretty well balanced since we've had the pool, though we did convert to a SWCG - which I wouldn't think would have contributed to this issue. So I don't know if we've caused them to look worse or it's just been the timing. The first year we had the pool, didn't know anything about pools, had a pool company come out to show us the opening procedure. They handed me a bottle of test strips and told me to only worry about three of the four (told me stabilizer wasn't important). I later found this site and bought a real test kit. Apparently the stabilizer wasn't important because it was off the charts. The previous owner had been using tablets and apparently didn't monitor CYA either. I found TFP sometime in the first year of ownership and feel like the water balance has been pretty good since then. Feel like the chlorine and CYA had been high for several years before and have no idea if pH was monitored before we bought the house.
It's my understanding that the staining in the surface cracks is caused by cobalt leaching out of the layer under the finish layer on the steps. Tested calcium yesterday and we're at about 90. Not really sure calcium is part of the problem, but am going to do a little more research. Was interested if bumpy was having any luck slowing down his blistering by altering his calcium levels.
