Can you use a TDS tester that test has a test range 0 - 1999 ppm (mg/l) CaCO3 for alkalinity? I've got the conversion for my regent test kit, could I apply it to the electronic tester?
Unfortunately, you cannot use a TDS meter to measure alkalinity. TDS meters work via conductivity, and will detect any ion in solution. It is just an unfortuante coincidence that the units can be read as ppm CaCO3. It really has nothing to do with determining Ca++ or CO3--.