Quote:
Originally Posted by marvso
getting the hang of EZ WATER CALCULATOR. Pretty slick! Do you think one still needs to invest in a PH meter or are these calculations accurate enough?

I've seen the term "water calculator" used more frequently lately and thought it was worth clarifying.
These spreadsheets and online "calculators" are all
models, not calculators. There are mathematical calculations involved in the process, but are very much not calculators.
Calculator implies that if you put in the right inputs, you get out the "correct" output. The problem is there are thousands of input variables which you just can't completely know.
A model attempts to use a few known variables to get a decent representation of the system without knowing every last detail.
The authors of the various models have all used their own inputs and methodology to try and get as close to the "actual" pH across as many scenarios as possible.
So it's probably no surprise that these models all give different "answer" to the problem. This is because they are all using a small subset of the inputs in different ways. Ever looks at those hurricane forecast models with different lines for each model?
I guess I could have said "yes, you need a pH meter", but hopefully you have a better idea why.