I just measured my pool with the TF 100 testkit: [Edit to correct name of testkit:Butterfly]
Free Chlorine: 3.5
Total Chlorine: 4.0
Total Alk: 50
Cyanuric Acid: off the chart, somewhere around 150
Seeing the total alkalinity and pH are very low, I started by adding a 6 lb bag of Baking Soda.
I couldn't believe my Cya is 150, so I took a sample to the pool store to verify my own readings.
Pool store says:
Free Chlorine: 5.0
Total Chlorine: 5.0
Total Alk: 20
Cyanuric Acid: 80
How can the pool store's computer give readings SO FAR off from my readings?!
I'm especially concerned by the TA and CYA.
I got 50 TA, added 6 lbs of Baking Soda, then the pool store read 20?!
I got ~~150 CYA, the pool store got HALF that?!
I don't know which to believe, because they are so totally different.