Or leave it at 20% and tweak the pump run time to slightly less . That will give you like 15% would if you had it.
I do my pH testing in the kitchen using the light one the stove hood (60w bulb). I hold a white plate behind the tube to help me get the color match. It works better for me than outside.
Kim![]()
Can you set a SWG % of 7 or is it 5% increments?