I'd be happy to create a graph, but please excuse my ignorance since I'm not exactly sure what the graph should show. I have seen the graph of HOCl vs. OCl percentage (a single S-shaped curve) as a function of pH and that graph won't change due to CYA since the HOCl/OCl ratio is independent of CYA.
You mention a 3-hump graph, but I haven't seen that (or don't recognize it by how you are describing it). Can you point me to a Internet website or other link where I can see what you are talking about?
If you wanted to see how HOCl levels change vs. pH with different levels of CYA, then perhaps the thing to do is to only show HOCl (forget OCl-) absolute levels at a certain Total Free Chlorine (FC) level and show multiple lines on the graph representing different levels of CYA. This would show how the S-shaped curve changes in angle (flattens out) at higher CYA which means that you can't change HOCl as readily by changing pH when CYA is present. The main problem with such a graph is that the scale when CYA is 0 is hugely different than the scale when there is CYA present. I could show the HOCl level (the Y-axis) on a logarithmic scale which would readily accommodate the 0 CYA and high CYA cases, but I don't think this is the "familiar" scale used on the graphs you are talking about.
[EDIT] Or I can just show two graphs, one without CYA and one with CYA (say, with a level of 30 ppm), and obviously the scales could be different for the two graphs and yet each have normal linear scales that people are familiar with. This sounds more like what you were asking for. [END-EDIT]
Of course, I can just come up with something and you can give me feedback -- that's what I've done with some of the other graphs in The China Shop.
Thanks,
Richard
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