Persistent low pool pH

[PoolDoc]

Why can't I use powdered shock, cal-hypo, to bring up the chlorine level?

Because, then you have to account for the effects of calcium and carbonates and hydroxides added by the cal hypo. It might be OK, but it might turn your pool in to a milky mess. Without test results from your K2006, we have no way of knowing.

[CarlD]

If your calcium level goes much over 400ppm, your risk of a milky pool increases. All dry chlorine combinations have drawbacks. Cal-hypo's is rising calcium. Di-Chlor's is lowering pH and raising CYA. Tri-Chlor's is REALLY lowering pH and raising CYA, too. Lithium is insanely expensive and we have not seen or heard of it working any better. Only bleach/LC have virtually no side effects.

Carl