Richard Falk's Pool Equations Spreadsheet

I am looking for a pool chemistry calculator that (hopefully) could be ported to an iPhone or iPad. Richard Falk's Pool Equations Spreadsheet looks like a possibility; however, it appears very complex. Does anyone know if there is any documentation (other than the scattered notes on the spreadsheet) on the proper use of his calculator?

I am very confused about Initial and Goal values; both of which change depending on which buttons are pressed.

Any help would be appreciated.

I'll alert Richard to your question; I've been wanting a better documented version of that spreadsheet, myself. I'd like to have it audited, but I don't have the skills to do so myself, and those I know who do, and might be willing to do so, will need clear documentation. If you can persuade him on that point, I'd be grateful.

However you may be barking up the wrong tree on the app -- because an iPhone app based on his spreadsheet already exists (see poolcalculator.com ).

I'm not too interested in having PoolForum support a new version of such an app, because the versions that already exist inadvertently encourage people to chase numbers, rather than enjoy their pool. We fielded quite a few questions and problems here, last summer, that resulted from people following the PoolCalculator right into NeverNever land. I want a much simpler app, not a new and more exact one!

Of course, there's also a good chance Jason Lion at TroubleFreePool.com probably won't be too interested, because it's his app!

Outside of my site and TFP, the direct correlation of chlorine and CYA with respect to chlorine's efficacy is still considered premature at best, and pool voodoo at worst. But, it's that concept that lies at the heart of Richard's spread sheet.

Jason sold The Pool Calculator to pSiFlow Technology and unfortunately they have not updated the iPhone app at all, not even to fix a bug where it won't save your settings if the app is killed (i.e. not kept open in the background or if it's killed when the phone is powered off completely).

The spreadsheet was not intended for general use (i.e. it's for me, and not a product). You use it in basically one of two ways. You can enter Initial and Goal values and then you will see values in the blue areas below in the Goal column, but for greater accuracy you click on the "Calculate Acid/Base/Buffer" button to get values that show up in the yellow data-entry area and in the blue area to the right of it showing different units of measurement. Note, however, that this calculates the amount of carbon dioxide outgassing (if any) or amount of baking soda to add and most people don't care about that if they are just doing pH adjustment or other chemical addition. So instead, there is another button called "Calculate Acid/Base/TA" that you can click and this will change the Goal TA value to avoid any carbon dioxide outgassing or baking soda addition (i.e. you use this button when you are just concerned about adjusting pH or adding other chemicals and don't care what happens to TA).

The other way to use the spreadsheet is to enter in values in the yellow data-entry (under Difference) column for the chemicals you want to add. You then click on the "Calculate pH/TA" to see the result of adding those chemicals.

There is also a "Clear All Inputs" button that clears all the chemical inputs in the yellow data-entry (Difference) column and there is a "Reset Goal = Initial" that sets the Goal values to equal the Initial values. The "Set Initial = Goal and Clear all Inputs" can be used to add multiple chemicals and see their cumulative effects one at a time.

Finally, there are buttons for "Calculate CCPP" and "Clear CCPP" which are for the Calcium Carbonate Precipitation Potential where you put your numbers in the Initial section and presumably have a non-zero Calcite Saturation Index (CSI) and the CCPP calculation essentially precipitated or dissolves calcium carbonate to get to a zero CSI and tells you ppm of calcium carbonate.

The chemical addition calculations are straightforward and already in The Pool Calculator. The complex formulas are for calculating pH or amount of chemicals to get to a desired pH, especially for the weak acids. Jason basically just used a bunch of values he tested in the spreadsheet to come up with a table of values (or rough fitting formula) that works within a reasonable TA and pH range, but it is not an accurate or general formula. The pH Buffer Capacity thread gives a formula at the end that can be used to figure out the amount of acid or base needed to change the pH though the reverse calculation is more complicated and requires iteration.

Thanks, Richard.

Thank you Richard for the quick response and a very complete pool calculator.