Quote Originally Posted by pedsrn
My pool is vinyl, so I hardly ever check Ca+. I did check it today and noticed it is 60. It was well over 200 last August. I'm curious as to how that happened???
Possibilities:
  • Leakage / splashout, followed by water replacement. (Not very likely, since it would require that you lost 75% of your water in a single episode, or even more, if you lost, say, 50% per episode.
  • Scaling / precipitation. (Is your pool slimed, with what feels like sand on the liner / ladder / light rings under the slime?)
  • Testing error. (Have you changed test methods, or replaced old test strips with new ones? Test strips are inaccurate, but get much worse over the summer as moisture from the air or your fingers causes them to deteriorate.
There may be some additional possibilities, but those are all I can think of at the moment.

Ben
"PoolDoc"