Has anyone found a reliable conductivity tester? We've tried both homemade testers and flinn science testers and neither has consistently worked for us? Thanks
Is your issue that the tester always lights up with a dissolved solution of any powder?
One of the testers (our homemade one) always lit up on solution, the other (Flinn) never lit up which may have been from a bad lightbulb
I remember a couple years ago we ran into the same problem with our testers always lighting up, and we figured out the reason why the homemade one always lights up is because of strong vs weak electrolytes. Some of the powders will completely dissolve in water, and the presence of so many dissociated particles allow the solution to very effectively conduct electricity, which will cause the bulbs on the tester to shine very brightly. But there are other powders that are weak electrolytes, which will dissolve in water, but not completely dissociate like strong electrolytes. Those ones will still be able to conduct electricity, but not as well, so the bulbs will still shine, but the light given off will be significantly weaker. A good way to test this is to look at NaCl (a strong electrolyte) vs. sucrose (a weak one).
There are three possibilities for the Flinn one: 1. It's not on (it has an on/off switch), 2. the 9V battery is dead, 3. as you said, the lightbulb is dead. Check those before buying a new one.