Thats exactly what I thought, you do not have equipment for measuring. Its not such a big deal since you are in “soil”. You most likely wont need calmag but you should figure out EC of your tap thats for sure. BTW too much light can mimic literaly all kind of deficiencies, which do not respond to increase in EC other than serious burn. If your leaves are healthy further down the plant and top seems to be “deficient” your environment is not able to support the amount of the light you provide to the plants. In case you provide ballanced food with proper medium treatment ofc
Now that light thing isn’t a piece of information that I have heard or read. All I knew is that a light too close can burn or bleach the leaves. And the issue was actually with the leaves about half way up the plant so that’s another reason I believed light was a non issue.
Also from my knowledge, mobile nutrients will show on the bottom while non mobile nutrients will show deficiency at the top and calcium is a non mobile nutrient which is where my idea of a calcium deficiency came from.
my city lists the water ppm at 100, so I’d imagine it is pretty close to that and I do not use well water