The 30 day is one of "Chas's Rule" (Chas, a vauled contribitor to the fourm and a proffesional in the spa industry).
The rule comes from that typically new users tend to make a lot of mistakes in the first month, and kill the water and then try to bring the water back by adding even more chemicals.
This seems to be true more often than not, and is just part of the learning curve.
You seem to be an exception to the rule, (which is a good thing).