What are the proper ranges for spa chemicals?

[DJJ]

I see that the recommended ranges vary depending on what I read. My LaMotte tester says Total Alkalinity should be 100-150 ppm. I see another recommendation for 80-120 ppm. My paperwork that came with my spa recommends 80-100 ppm. My LaMotte tester recommends Calcium Hardness at 175-350 ppm. I see another recommendation for 150-250 ppm. My paperwork that came with my spa recommends 100 ppm. The only thing that everybody seems to agree with is proper PH levels. Most recommend 7.2-7.8. Can anybody tell me what the real proper ranges for these chemicals are?
Thanks.

[Sam]

The real answer involves using the saturation index which takes all of the factors into account (including temperature) to determine if your water is balanced.  This this tends to be a little too heady for the average consumer, so we use generalizations.  All of the ranges you showed are generalizations and that's why there is variation.  I usually tell people 7.2 to 7.6 for PH, 80-150 for alk, and I don't really worry too much about hardness unless we see a symptom that could be caused by the hardness level.  100 to 450 is probably fine for most situations.

So, short answer is somewhere in all of the ranges you posted is fine.