Calcium in tap water

it just shows why you may need a slightly different mix of nutes than someone else.. If you see any major lockout, i'd look into calcium levels, for example. BUT, it is only a problem if you add too much.. so it could be a good thing.. if you don't need to supplement Ca at all, that is one less product to buy.. many lesser quality nute lines leave it out because it can cause a precipitate to form in some contexts. you will often see the component that contains the Ca as a separate part of the mix and you should generally mix it in last after everythign else is dissolved and at proper concentrations. by using RO or otherwise filtered, you can more easily use a standard formula without adjustment -- it makes your garden apples to apples with another in regard to fertilizer (*simplified, there are other wrinkles like VPD that will impact optimal concentration). This isn't necessarily "better" but is definitely simpler and easier to hit the ground running with fewer adjustents. I have very hard water. You may want to start near my "ballpark" of Ca PPM. You can see a table of my formula that i mix up with PPM per molecule as well as the total of the mix, based on guaranteed analysis labels that you *can* trust. If you are in soilless, knowing this stuff is very useful. if you know what you feed you can more easily adjust to what you observe in the plant. Even with a soil grow it is helpful. It can help you learn that balance as you ramp up fertilization as initial nutes run out in the soil. manic botanix has a nutrient ppm calculator (google). if it doesn't involved specific gravity you can use my spreadsheet. google drive link in my main GD profile comment section - sort by newest and it should be at top or near top. Specific gravity may or may not work with my spreadsheet. i never verified it. this depends on w%/w or w%/v labels.. instructions are in cell A1's comment. No macros, only a very basic spreadhseet. never download from a different source as spreadsheets can be a bit dangerous. This is why excel or calc will warn you if there is a "Macro" ... never open an unknown spreadsheet that has a macro.