unable to maintain chlorine levels

[Coman]

took awhile to re-read the whole booklet, but...
Protected Chlorine: FC + Stabilizer -> Protected Chlorine, page 26
PHMB and Heavy Metals: in both tables, pages 43 & 44. No formulas/test procedures given.
CYA Stabilization: with Table K, page 63
Saturation index: see glossary and the instructions on the back of the Water Balance Calculator

[PoolDoc]

Protected Chlorine: FC + Stabilizer -> Protected Chlorine, page 26

Not an equation; it's a half-a'd way of expressing an idea.

PHMB and Heavy Metals: in both tables, pages 43 & 44. No formulas/test procedures given.

Not relevant to chlorine pools.

CYA Stabilization: with Table K, page 63

Ok. I'll have to explain. But the short version is, IGNORE IT!

LONG VERSION: With respect to pools, and most water treatment activities, alkalinity is the pH buffering over a specific range of pH values. (There are more technical definitions; you can Google if you want them.) Buffering is a measure of the resistance of a specific solution (YOUR pool water, in this case) to pH change over that range. In pool water, you have "TOTAL" and "CARBONATE" alkalinity. "Total" alkalinity looks at the absolute buffer status of your water; "carbonate" alkalinity looks at the proportion of the buffering caused by carbonates (HCO3, -HCO2, =CO2) in your water. Virtually all pool tests measure TOTAL alkalinity, not CARBONATE alkalinity.

Typically in pool water your TOTAL alkalinity is a combination of the buffering provided by borates (borax), cyanurates (stabilizer) and carbonates (pH UP, Alk UP, etc.). The index you are looking at attempts to estimate the cyanurate alkalinity, and then deduct it from the total alkalinity to approximate your carbonate alkalinity.

There's considerable debate whether this distinction is meaningful in concrete pools, or pools with gas heaters . . . but it is NOT significant in your pool.

Saturation index: see glossary and the instructions on the back of the Water Balance Calculator

SHORT VERSION: Doesn't really apply to you, but you might want to keep a negative-ish index, to avoid scale in your solar panels. PoolCalculator.com offers an easy way to do this -- but do NOT obsess over it!

LONG VERSION: The various saturation indices attempt to determine whether a given water solution is likely to deposit calcium scale, or to dissolve calcium products present (like water). This calcium index is, through a variety of arcane and doubtful deductions, then taken to offer some guidance about whether that same water is likely to dissolve iron (or perhaps, copper).

All of the indices (there are a bunch!), do some sort of mathematical jiggery pokery combining the water's temperature + pH + CARBONATE alkalinity + calcium hardness. There's been a bunch of discussion here (China Shop) and on TFP (The Deep End) about which index is 'best'.

Some of the college professors who were the original developers of these indicies, have cast doubt on their applicability to pool water . . . but that hasn't slowed pool chemical companies down. They *love* anything that gives
(a) a wizardly calculation that tells you to add more chemicals each time you visit, AND
(b) that can be performed auto-magically with a computer, calculator, or other electronic gizmo by pool store attendants who flunked junior high math,
(c) using dealer test results, whether they are accurate (titration) or mostly bogus (test strips).

A lot of people buy Taylor K2006, because of my Best Guess chart, my websites, and some 'me-too' sites. But, the K2006 is a small fraction of Taylor's pool business. They know who we are, and they know why we recommend what we do, but they also know that pool stores HATE what we do. And pool stores sell a LOT more of Taylor's overall product offerings, than all the BBB method websites out there.

So . . . Taylor stays on the NSPI / APSP / NSPF bandwagon because . . . they know which side their bread is buttered on!