I'm in the process of getting a ph pen that&#...

Unless you are taking daily readings, usually more cost-effective to just buy 100-pack of strips for 5-10 USD. The ones with 4 color-code gives enough variation to easily decipher vs 2-color options. .5 pH is good enough resolution to see if something is going off kilter. The cost of callibration fluid, hassle of keeping and storing said fluid, and the delicate nature of the probe means it will cost more and come with greater hassles/effort. Even if it adds up to 1-2 dollars less per 10 years, the convenience of single-use strips is worth it.

Ffs, look for yourself if u don't belive be https://dutch-passion.com/en/blog/a-visual-guide-to-cannabis-deficiencies-n987#calcium👈