Question on TA change calculation in PoolMath

[Cluckr7]

Is the TA calculation in pool math an “approximation” like PH or should it be pretty accurate?

For example, over a period of a week when I’ve added enough MA that should lower TA by ~25, my testing (TF100) shows more like a ~10 drop. This is pretty consistent. I do have high TA fill water but based on my daily evaporation rates I don’t think that would account for anywhere near that difference.

 

[ajw22]

Everything in water chemistry is an approximation with various variable affecting the results.

Now that you know you get a 10ppm TA change you can plan for it.

 

[Leebo]

The TA calculation in Pool Math is a “close enough” calculation. However, there are a few variables at play when it comes to real-world testing and results. First off, the margin of error in your TF100 test kit is ±10ppm. So, there's some variability right off the bat. If you have high TA fill water and you're adding it regularly, even with consideration for your evaporation rates, this can also influence the TA level more than you might expect. Another important thing to consider is the consistency of the testing drops. When you're using the drop test for TA, ensure you're wiping the tip of the dropper bottle between drops. Static electricity can sometimes influence the size of the drops, which can throw off your results. Taking all of these factors into account can help provide a clearer picture of why there might be some discrepancies between what you expect and what you observe.