This test only reads to 3ppm of FC. If I want to test for higher levels of FC, can I simply add the water to a larger container 1:1 from the test tube and just add 3PPM each time until the color drops off? Thanks in advance.
No, the test drop size is calibrated to the test container size. You can dilute your pool water sample with non-chlorinated water and test the result by filling the sample tube. One part pool water to one part non-chlorinated water will test at half the actual reading etc..