You'll have a lot easier time of it starting with RO water. That is the most economical 'solution' for high PPM - dilute it, or start with RO and add just enough calcium as needed.
I live in Phoenix, and we have *hard* water, similar to yours. Cities put calcium carbonate into the water (if it isn't there naturally) to buffer the water to an alkaline state. You do not want acidic water running through old metal pipes. Besides hardening the water and adding too much calcium in many cases, it buffers the water to avoid dropping into acidity. So you need to counteract this alkaline buffer to some extent. I'm using the GH nutes, plus
calimagic, humic acid and silica. My pH starts out slightly alkaline (RO water) but ends up around 5.9 by the time I get done mixing all my nutes. I then add a capful of pH UP to get the nute mixture to 6.0 and dump it into my reservoir. From there, if it tries to rise, a
Bluelab controller feeds it a bit of pH DOWN every 10 minutes until it is back to 6.0. On occasion I see my pH drop to 5.9, so I manually add some pH UP then. It is the nutes themselves both lowering pH and buffering it to stay there.
If you are growing in soil, the pH isn't going to matter as much because the soil will buffer the pH to where that soil wants it. But if growing in coco or hydro or rockwool, you do need to control input pH closely. (I'm growing in coco coir, and I've got my pH set to 6.0, which is lower than you would want for soil. I use a pH controller to carefully keep it at 6.0.)
It will help if you post pics of your problem leaves as soon as you see problems.
That said, your PPM is high (too high) for seedlings, but no big deal for mature plants. You might be overwater, and/or over/under feeding them, but we have no idea from your description.