CLEAR BLUE COPPER TEST STRIPS
$19.99
These are the best tool for testing low levels of copper in swimming pools and hot tubs. It is important to keep the copper level in the ‘OK’ range to make sure that the minerals are sanitizing effectively without causing a buildup or using up the mineral source too quickly.
Your mineral system may add additional minerals to the water beside copper, however, copper is the easiest to test for. If the copper level is correct, the other mineral levels are also correct.