Hello. I moved to a home having a newly resurfaced (pebble) pool and knew absolutely zero about pools and pool maintenance a few months ago.
A pool service shocked the pool using granular trichlor, which sat on the pool service for a few days (even though I was told initially it would dissolve in a few hours). I'm sure some staining took place where the granular trichlor sat on the pool surface, but being a newbie pool owner, I didn't really notice it at the time. A month later, on a weekly service visit, I am informed I have no chlorine in the pool, so it must be shocked again - granular trichlor once more. This time, it was obvious to me where the trichlor laid on the pool surface, it was leaving behind stains. Someone from the pool service has since verified the granular trichlor was indeed staining the pool. The color of the stain is difficult to determine because of the pebble, but I'd guess brown-ish(?).
I've since found this forum and have learned a lot. I have a Taylor 2006 test kit and have been testing for about the last 2 weeks while keeping the pool service going. Here are my current numbers (though I don't have any numbers for the time in which the stain occurred, unfortunately):
FC - 2.5
CC or TC - < 0.5
pH - 8 (possibly a tad more, but Taylor only goes to 8.0)
TA - 90
CH - 230
CYA - 68
I realize my PH is high and chlorine is low (based on my CYA of 68). My saturation index is about a 0.4.
Q1: Should granular trichlor be staining my pool's surface? The pool service says it is how they service all of their pools and that after an acid wash, the same treatment should not stain my pool (they believe the pool was never acid washed). The last thing I want is to acid wash the pool and then it get stained again by throwing granular trichlor at it.
Q2: Can anyone advise me on what I can try to remove the stains other than a complete acid wash?