So. I go up to pool store for a refill. I ask about percentage, guy tells me “12.5, says it right on the container.”
Y’all don’t know me, but I don’t do well with people treating me like I am stupid. So, I say, “Is that so? Well, can you explain why, when I test afterward, the resulting FC level is consistent with 10%, not 12%? And it’s not that my water volume is off. I’ve tested enough to be sure of that number.”
He goes back to talk to someone in the back, and comes out and tells me sheepishly, “It’s 10.5%.”

Y’all don’t know me, but I don’t do well with people treating me like I am stupid. So, I say, “Is that so? Well, can you explain why, when I test afterward, the resulting FC level is consistent with 10%, not 12%? And it’s not that my water volume is off. I’ve tested enough to be sure of that number.”
He goes back to talk to someone in the back, and comes out and tells me sheepishly, “It’s 10.5%.”