Quote Originally Posted by chem geek

As for your comment about the Taylor Watergram's very construction not allowing for accurate results, I don't understand that. It looks like I can easily get accuracy of 0.1 LSI. They make an assumption for CYA level since the watergram uses TA instead of Carbonate Alkalinity, but that's a minor error since a change of 30 in CYA results (at typical 7.5 pH) in about 10 TA change which results in a roughly 0.05 LSI change. Of course, Ben made the point about all the errors in the individual measurements introducing error in the LSI, but that's true whether the watergram is used or not.

Richard
The TA can be ajusted for CYA and that result used on the watergram so that point is moot.