SI can be useful...
But don't live or die by it. If your other numbers are good, and your pool is clear, don't mess with stuff to improve the SI.

But if you are having troubles, the SI may help you pinpoint what is wrong.


Me, I keep it simple and stick to Ben's test kit...You'll rarely have a problem that it cannot identify--and 98% of the time that problem will be due to metals, bacquacil, or ammonia-based algaecides in the water.