Question about water balance.

So I do a lot of work with pools, so Im good at balancing water chemicals for pools. But made me wonder what is the best balance For the water I use to water my plants? I read a lot about ph, which I keep it around 6 to 6.5. But what should my ppm be for alkalinity and calcium? Pool water alkalinity needs to be 80 to 120 ppm calcium 250 to 400ppm, should plant water be a lot lower?

Many of us use that much Calcium but it is always at about 5 to 1 ratio with Magnesium. We do in fact use nutrients as buffers in many cases. Basically say you provide your nutrient mix and to start it's a light solution because the plant is little/tender. But she eats up a lot of the Calcium and all of the Nitrogen which obviously throws your pH out of balance so we need to replace it or in hydro swap out the reservoir to be sure. Most the time in soil you won't have any issues because these days we are just following what's been found to work.

Here's some good reading on pH.. This guy is a chemist that wanted to show people how to grow food for cheap, window nft gardens and mixing your own cheap nutrients to eat on. These are links to a blog pertaining to pH from said chemist. (Above this post I have more links)
https://www.rollitup.org/t/hydrobuddy-free-hydroponic-nute-calc-by-chem-scientist-botanist-mix-own-nutrients.368514/#post-4664889