ORP reading vs test is WAY off. Can residual Hydrogen Peroxide, Ascorbic Acid, or Sequesterant cause this?
Orp is reading in normal range- (fas Dpt)Test is 3x higher
I shocked/ superchlorinated a spa (1000g) to break combined cl. Following that:
Used H2o2 to drop cl levels.
Used AA to remove stains.
Added Sod Hypo to get a residual. (<1)
Turned the auto feeder(s) back on.
The spa is fed by automatic orp/ph readers. In 12 hrs they fed the Cal Hypo to >10ppm, and the pH is testing high (off the scale) which may be due to high cl?
The ORP on the feeders (and a secondary ORP reader) read normal and are feeding cal hypo accordingly (disabled now)
So, What on earth is causing the ORP reading to be normal, when in fact the cl is 3-4x high?
and, at what cl level does pH testing become invalid.