We have a new hot tub and we have had someone putting in the chemicals for the last little while as she has one of her own and didn't mind doing ours. In attending a seminar on how to clean and maintain we decided we wanted to learn how to do it ourselves. We were given a list of chemicals and amount to put in and when to put them in. Our friend came over and went down the list with us and put the chemicals in. For the first time after adding the chemicals my mother had bad itching on her arms and my sterling silver ring tarnished. We were told to put each chemical in at least three hours apart for them to work properly but our friend puts them in all at the same time and when she puts them in it is not in the same amount as the list given to us, she only puts in a certain amount the list calls for quite a bit more in certain ones. I was wondering if the chemicals will work better if they are put in three hours apart or if it's okay to continue putting them in all at the same time.

I own a pool & spa service company, and we always put all of the chemicals in at the same time. It would be less than cost effective for us to hit every service stop more than once in the same day. As far as the amount of chemicals to add, it all starts with using your test kit to find out where you are at. If you are completely out of chlorine, you would add more than if the chlorine residual was a little low. A spa, or hot tub holds very little water, and a little bit of chemical goes a long way. You can always add a little more if your test kit indicates the need to do so.

Normally, skin irritation is mostly caused by the PH being too high, or too low, but a super strong chlorine level will also cause this problem. You didn't say what kind of sanitizer you were using, but ALWAYS USE YOUR TEST KIT before you add anything to the hot tub. If you can find out how many gallons of water are in your tub, there are charts available to tell you exactly how much of each chemical to add based on your test readings. Hope this helps.
Mike