How often do you find you need to add water to the pool? New pool, and my water level is a couple of inches below the half way mark of the tiles. When you add water from the garden hose, what effects on the chemestry do you find?
Depends on the amount of evaporation and/or rain you get.
Adding water should have a very minor impact on the chemistry. Most of the solids (CH, salt, CYA) should be unchanged (well CH may go up a little). And the fill water TA and pH could have a minor influence.
Best to test your fill water so you can anticipate any effects prior to filling.
For example my tap water is high in TA so I know my acid demand will be rise slowly when I top off the pool.
Also I see a slight dip in FC levels due to the fact that municipal tap will have a low FC, .04ppm compared to the pool at 7ppm
My fill water is also fairly low in CH at 110 so any rise is minimal.