Had this since i opend the pool since then ive tested the water only 1800 ppm so its actually low so i added salt replaced the salt cell and still no change it wont even let me try to calibrate it just stays locked on H.H. everything else seems to be working just fine only thing i can find is replacing the display which makes no sense at all or the tri sensor but there are different codes for that which i should be getting if that were to problem so im at a loss please help