I live in the Toronto Ontario area and went to two seperate pool stores for water testing last night and reiceived very different results.

Pool store one uses strips and a scanner to scan the strips colour, which I find highly suspect and am tempted to ignore the results, even though they tell me since the scanner checks the colours that it is very accurate.
Pool store two uses the standard drop tests with colour changes.

At pool store one and two my chlorine level and PH were identifed as being the same, but CYA at pool store 1 was 10, and pool store 2 was over 100. I have the taylor 2006k test kit and my test shows CYA of 30. At pool store one my calcium level was 260, and at pool store two it was 110. My taylor 2006k test kit shows it at 110.

The main reason I went to the pool stores to get my water tested was that I wanted to double check my results and purchase calcium chloride to bring my calcium level up to about 200 -230 ppm. I have a vinyl pool with a heater, but the reason I want the correct calcium level is that I have a concrete surrounding the pool and don't want corrosive water to be pitting my concrete.

At this point based on the results I am not sure if I should add calcium or not, as pool store one tried to tell me that our water out of the tap is 250 ppm which is what I used to fill the pool with. Yet my testing and pool store 2shows my calcium level to be low.

At this point I am tempted to believe my tests and pool store two and add about 10kg of calcium chloride to bring my calcium level up to around 210 ppm, assuming pool store 2 and my results are correct.

What would others do in my situation ?

Thanks