Here’s the improved version I mentioned that accounts for the water’s ppm: Feedrate calculator v2 (Excel)
When I asked if anyone needs different units for Column C, I was thinking of something like ml/L instead of tsp/gallon. @jdw threw me a curveball by reminding me of Jacks 321. Accommodating their dry fertilizers in my spreadsheet is tricky, but I’m working on it.
Jacks 321 is very popular, so I hope to add a tab for it. Thanks, @jdw, for alerting me to the desirability of incorporating it.
BTW, my description of the idea behind these calculations was…muddled, to put it politely. That idea has nothing to do with maintaining a consistent runoff ppm, as I suggested.
Instead, the idea is to maintain a consistent ppm in the pot. It’s like estimating how much gas you need to add to your car’s tank to top it off.