Is there a reason 29% muriatic acid is not an option in the "Effects of Adding" menu? It is available in the dropdown of options to lower pH in the actual pH measurement/log screen, but not Effects of Adding.
On the same topic, is the Effects of Acid menu correct for 14.5% muriatic acid? For example if I set my current pH to 9 and a target pH of 8, and set in the "What will you use to lower pH" option as 14.5% muriatic acid, it tells me to add 56 fluid ounces (13000 gallon pool). So that would stand to reason that 56 oz of 14.5% muriatic acid would result in lowering pH by 1.0. But if I go to Effects of Adding and put in 56 fluid ounces of 14.5% muriatic acid, it tells me it would lower pH by 0.5 - so which of these is correct, and/or why are they different?
If I hazard a guess, it’s because Effects of Adding is only a very rough approximation for pH calculations, which ties into your second question.
On the Effects of Adding page note the warning listed at the bottom:
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My understanding is the Effects of Adding page does NOT link your latest TA/pH/borates when estimating, hence the warning that it’s good only for small changes within certain ranges.
When calculating acid additions from the latest test results section this calculation does indeed pull and use latest TA/pH/borates for calculation of pH effects, so it is more accurate (though not completely accurate). Always use the other section of the app with the Target and Current pH values to calculate pH adjustments. Actually for any adjustments. The way I think of it is Effects of Adding is to see what all effects a particular chemical may have, but Effects of Adding was not designed to actually be used to calculate the amounts of something to add.
For example using my hot tub, I can use the FC section to calculate a FC increase from 3 to 6 ppm on my hot tub. I select dichlor as I need some CYA. It says add 0.3 oz of dichlor. If I want, I can now go to Effects of Adding page and put in 0.3 oz of dichlor, and I can see dichlor will in addition to adding FC lower the pH, raise the TA, and add salt. Note the same warning that the pH calculation is approximate.
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Basically I think of the Effects of Adding as a curiosity for finding out what what all a particular chemical may do in addition to it’s main function, but only
after I use the addition calculators to calculate the dose of chemical I need to add.
Does all this make sense?