I remember when I first started testing my water I had all kinds of questions and thanks to the experts here I have maintained absolutely crystal clear water for 6 weeks now with no surprises.
The reason I'm starting this topic is b/c I remember there was a little debate on what the ph and alk will do over time based on your tap water levels. Some said that they would tend to gradually try to go back to there tap level. While others had a couple of differing theories. Well here is what my water has done thus far.
First off let me say that my tap water has a ph of 8+ while my alk is 200+ and that I use dichlor and a buffered mps product. I follow the post soak dichlor dose method and shock with mps 3 out of the 4 times a month with the other being with dichlor.
After my inagural water balancing of my spa to get a ph to 7.6 and my alk to 110, both have been decreasing slowly. This is even with adding an 1'' or so of tap water a week. I haven't added anything to my water besides dichlor, buffered mps, and 2oz of defender 2x. It's been 6 weeks now and my levels are at 7.2 and 60. So I added 1.5 oz of baking soda to bring them back up. This was the first time in almost 5 weeks I've added any kind of + or - chemicals to my water.
Just thought I'd share my own findings for any of you water chemical experts.
CHAD