I am confused. I thought I had this all figured out, but now I am unsure.
First off, here are my numbers:
FC - 2.5
CC - b/t 0 and 0.5
PH - 7.5
CH - 80
TA - 90
CYA - 40
Here is what has me confused. Last night I added a ton of CalHypo. I tested the water about 2 hours after adding it (a couple of hours before sunset, but late enough that my pool is completely shaded from the sun) and my FC was 6.0. Thus, I lost 3.5 FC overnight. That is alot more than my pool usually loses. Thus, I am concerned that I might have some unseen contaminants in the pool. One other thing...I have alot of stuff that looks like sand on the bottom of my pool. I thought it was undissolved chlorine so I swept it up to mix it, but now I wonder if it is dead algae or something else.
Here is what I am wondering:
Looking at the CYA / CL guidelines (both from this forum and the poolforum), the minimum CL for CYA 40 is 3. What exactly does that mean? Is water under 3 ppm FC going to allow algae to grow? Or is it simply not as effective but still effective enough to kill stuff?
I have not allowed my FC to get to 0.0 but it does drift into the 2 range frequently before I add Chlorine. Do I need to be ensuring I keep it over 3 at all times?
Thanks in advance.