The other day I noticed a very hint of yellow haze on my white fiberglass pool steps. There was a definitive yellow water line, and it seems to clean up a bit when I scrubbed with a magic eraser or brillo pad. I scrubbed enough that its only noticeable in the dips of the treads on my stairs. I'm also paranoid and think I notice an ever so slight yellow tinge in on the liner in places. This would be places where my super old sun bleached out liner is typically the white-est.
Based on my first full analysis below with my ultra test kit recommended here, I added enough pH increaser to bring that up to 7.7-7.8.
pH 7.3 - 7.4
Today, my pH was 7.6 and FC at 3.5 and CC at 0. All others are the same. I have a propane pool heater, so I'm concerned about copper stains. I have a copper test from the same place I purchased the test kit, and it shows zero. I tried putting a tri-clor puck on the steps for 5-10min, but it didn't do anything since the yellowing is in the dips of the treads.
We are in moderate drought here in Massachusetts and the pollen has been off the charts. I've been pulling out enough oak tree puke from the filter to fill about 2.5 gallon buckets daily, so keeping everything tidy has been impossible. This is my second year with the pool and didn't notice anything like this last year. Any thoughts on what the yello may be?