powder left from bleach evaporation

I have a question and an observation/question for the chemistry experts on this forum.

First, my question: What is the powder that's left over after bleach evaporates? Is it salt? Whatever it is, if you mix it back with water, it won't make bleach again will it?

Next, it has been my observation that running somewhat higher CYA levels does NOT increase the amount of maintenance chlorine that you need to add. Yes, you will need more to get the initial level higher or to shock. But, once you have the higher level, it takes the SAME AMOUNT to maintain that higher level as it would to maintain the lower level that you would have had, had you been running lower CYA levels. Are my observations correct?

The powder left is basically salt. It might also contain some sodium hydroxide or sodium carbonate. No, it won't make bleach if you redissolve it.

You are correct about your observation on chlorine usage and CYA level. In fact, under some conditions, higher CYA can actually lead to a lowered overall chlorine usage if a good part of the chlorine is lost from sunlight in that particular pool and not from other causes.

I'm one of those who can tell you from first-hand experience that higher CYA levels in my pool (70-80) noticeably reduce my overall chlorine usage!!

Janet