Uh-oh - I have not purchased the TFP test kit as yet. Being my first pool, I figured that in order to fully appreciate the accuracy and detail of the TFP kit, I needed to try maintaining the pool with the guess strips first (PB also provided a container of the strips).
So far its been easy using the guess strips. I use it more as an indicative of where the pool is heading. When I started the salt system, I saw the chlorine levels going down - increased pump time and also increased salt cell to 60%, the readings came back up. Cyanuric acid was around 75 to 100 when I was using the trichlor pucks. After a bit of rain and having the SWG on for a month, its closer to the 50 mark.
The PH is the only troubling item - maybe because I dont want to believe that the pH is higher I added a gallon of acid a week ago and pH seemed normal - but it has been climbing again - I've read that its not uncommon with SWG and a new pool for the pH to creep upwards.
Since it is so simple to use the guess strips, I am prone to test the water daily - just as recommended on the TFP tests.
The guess strips also have specific instructions to be followed - dont swish the strip inside the water, it should be a quick in and out - I leave it inside water for 2 to 3 seconds tops. Dont wave the strip around like a polaroid camera photo - keep as steady as possible in horizontal position for 15 seconds. Then compare the colors. Surprisingly when I first used the strips without reading the instructions, it seemed natural to swish the strip inside the water and also wave the strip to get the water off it - both strict no-no's
So far so good. I do know that the first time I have an issue, I will be buying a better kit.