Only thing "gassed out" is the mind of the pool store employee who told you that! This is CLEARLY an example of testing error or you actually have a very high chlorine level that is bleaching out the DPD test. Test with OTO (turns yellow) and if the color is darker than bright yellow (orange, brown, or reddish after standing a few minutes) then you have very high chlorine levels and the DPD test they did (or the strips) are bleaching out!
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Welcome to TFP! For a wealth of pool care information please check out our free Pool School. If you are in need of specific help then we encourage you to Register and ask us here in the forum!