Hi I have a new pool, it was finished 5th October and contain about 10,000 gallon of water. The pool is plastered with florida gem, and is going to be a salt water system but we have not yet put salt in and are using a chlorine tablet floater and chlorine bleach to keep the chlorine up this seems to be fairly stable.

My problem is that we have a calcium hardness of 320, we use rain water and Ro water so was surpirsed by this but on testing our rain water tanks we discovered that they contain calcium. we have no supply usable to lower calcium.
PH is currently 7.2 but does seem to change a bit
Alkalinity is 40

Taylors water gram is telling me that the water is reasonably balanced but everything I read says that the alkalinity should be between 80 and 120 , every time I try to get the alkalinity up the PH goes up and if I use muriatic acid to bring down the ph the alkalinity goes down. Am somewhat confused.

1 - If the water gram says the water is balanced is that ok?
2 - If my alkalinity stays at 40 will my ph be stable?

would appreciate any advice, we will need someone to look after the pool when we are not here and want everything sorted before I try to get a local to take over.

Thanks for any advice it will be much appreciated