If the LFS is reading 0, how are you getting 1ppm? What else do you have in your tank? If your test result shows 1ppm but the LFS shows 0 ppm that means 1. one of your test result is wrong ..... could be the lfs or could be you, OR 2. If LFS says 0 and you get 1, you are somehow introducing chlorine to your water. RODI should always read 0 for chlorine. I am not absolutely positive on this, but I think chlorine could cause issues with cycling the tank. Also, when you start doing water changes in the future, if you have chlorine in your water it could be bad for your livestock.