Hi, I'm a new spa owner. I have a decent background in HS and College chem, so I'm comfortable using the reagent test kits. I am using a Taylor K-2006C. My SI currently is 0.1 which I'm happy with. I like to run my tub on the cooler side as here in Vegas it's been incredibly hot...so I keep it in the 86-96 degree range if overnight temps permit. As of tonight my TA is 80, CH 275, pH 7.6, FC 0.2, Temp 96F.
My question is when testing CYA do you measure the level when the black dot in the comparator FIRST disappears as I'm pouring the sample in, or when the sample is fully settledand the dot is PERMANENTLY hidden?
If it's the former my CYA is around 80, if it's the latter then the CYA is around 35-40.
Either way I don't want to keep adding Dichlor. The spa was only filled 9 days ago and used 2x. I also installed in the filter a Nature2 mineral sanitizing stick so I don't need to add as much Dichlor.
Should I switch to plain Chlorine bleach as I've read elsewhere to keep the CYA from increasing?
I will be getting a water softener in the next 8 weeks so my next fill will have a different CH.