I recently got certified as a Chemtrol field service rep and got my two Chemtrol 250's online again after years of disuse. This has allowed me to target my free chlorine levels in the 1.5 to 2.5 range without fear of dropping below one. We use the standard Taylor DPD chlorine reagents for thrice daily testing. I have been trying to use FAS-DPD for chlorine in my more comprehensive slate of weekly tests. What I have found is that the FAS-DPD test is wildly inaccurate at PPMs of 2 and below. For instance, yesterday I got a 0.4 FC in water that was clearly 2.0 as measured directly with DPD reagents and indirectly by ORP. I tried to confirm that this was a known problem by contacting Taylor but couldn't get through and didn't get a call back.
Looks like my FAS-DPD kit is going to be collecting spider webs until my next liquid Code Brown incident.
Looks like my FAS-DPD kit is going to be collecting spider webs until my next liquid Code Brown incident.