pool math hot tub

When I use pool math for my spa do I label my spa as fiberglass or vinyl? Or does it even matter? My spa is on its own from my pool so it’s a stand-alone cal spa about 425 gallons.

I'm a new spa owner following the How do I use Chlorine in my Spa (or pool)? approach to maintenance. I'm also using the Pool Math app to log my upkeep and calculate any chem additions. I recognize the app is mostly for pool use, but is it possible to change a setting somewhere so that the...

So I'm a great fan of TFP's pool math and used it to SLAM my green monster pool. Success! Thank you to all who continually contribute to this site! Now we've added a new hot tub. I have read and reread the "using chlorine in a hot tub" article. How do I use Chlorine in my Spa (or pool)...