Memorize the CYA chart?

[DCAG]

I was just looking at the CYA chart.

For the newbies, is it safe to remember the chart this way?

1. To know your recommended FC take your CYA # remove the zero, and add 1
2. To know your recommended shock level take your CYA # remove 0 multiply by 4

Or is this how everyone remembers it, and I'm just catching on now?

Dan

 

[PaulR]

Your shortcut certainly works for "normal" CYA ranges.

If you look at Chem Geek's Chlorine/CYA chart (which the Pool School article is based on) the footnotes describe how the FC levels can be approximated by a percentage of the CYA level. Which is exactly what "remove 0 multiply by 4" calculates (i.e. times .4, or 40%), and reasonably close to what "remove 0 add 1" does.
--paulr