phishfood Posted January 11, 2014 Report Share Posted January 11, 2014 K-2006 Tested TC (10ml sample) after adding second step get pink to show CC Takes two drops to clear .. Hmm, 1ppm CC wow. Do 25ml test takes 4-5 drops to clear CC so to be safe I assume 1.2ppm CC Go to pool calc and scared to not reach breakpoint, add 1 cup 2 TBsp Clorox ultra. Test, at 18ppm chlorine (CYA is 50) Leave cover off for six hours but starts raining (overcast all day, shocked a couple hours before sunset) Wait wait wait Test chlorine level now at 8 ppm Drop in five drops to check for CC and ... PINK AGAIN!! What did I do wrong?? Quote Link to comment Share on other sites More sharing options...
chem geek Posted January 11, 2014 Report Share Posted January 11, 2014 If you measure the CC too soon after a soak then it will measure higher. CC doesn't break down that quickly. It is best to measure it just before your next soak. Also, in a spa some CC is pretty normal and if it's not smelly then it's likely to be chlorourea which is fairly innocuous. 4-5 drops in a 25 ml sample is 0.8 to 1.0 (not 1.2) ppm. When you tested after waiting, showing pink in a 25 ml sample just means 0.2 ppm if it goes away with one drop so how many drops did it take after waiting -- was it still about 5 drops (1.0 ppm)? Quote Link to comment Share on other sites More sharing options...
phishfood Posted January 11, 2014 Author Report Share Posted January 11, 2014 After shock Test was done with 10ml sample ... Took two drops to make CC test turn clear. Quote Link to comment Share on other sites More sharing options...
chem geek Posted January 11, 2014 Report Share Posted January 11, 2014 So that's a CC between 0.5 and 1.0 ppm. If there is no odor, then I wouldn't worry about it. If the spa has somewhat heavy usage (every day or two), then there can be a buildup of slow-to-oxidize organics such as urea but chlorourea is relatively innocuous. If your overnight chlorine demand with no bather load is high -- more than 25% per day with hot water and no ozonator -- then you could consider a decontamination. If the spa is newer or had not been maintained properly in the past (e.g. a used spa), then using SeaKlear Spa System Flush or Ahh-Some can remove any biofilms that may be stuck to spa surfaces (including piping). Quote Link to comment Share on other sites More sharing options...
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