Water quality

Hi wondering if anyone can help me with this..

My plants struggled on 2 attempts so far so i want to start at the basics this time.

This is my water report.. from tap seems to be very high in calcium? So am i right in thinking i need to use a different water than tap? Or just dont use calmag? Magnesium content is very low so wen im adding calmag im just adding extra calcium as well to the already high calcium content? Sorry if this doesnt make sense just trying to learn and understand to become a better grower.

Im growing in pure coco btw.

Tia

It comes down first to whether your coco is buffered adequately. Once it is, it won't rob your cal/mag inputs. If your good in that regard, then using water with a calcium content will increase your uptake of magnesium. I'm not a DTW coco grower but I do grow in a coco dominant fabric raised beds. My tatget ratio of calcium : magnesium is 6:1. But in organic No-Till you can simply add a cal and a mag source and let the microbes work it out. Come mid flower tho, I'll start to supplement magnesium, manganese, sulfur and boron independently.
Not practical for the common homegrower, but I'm not following a nute recipe. And organic NoTill is a different animal vs. Regimented Bottle fed that follows a schedule.

Point is, if your cal inputs are up, simply increase mag. Any excess will simply wash out and away

Can't go wrong with RoDi- 0ppm