Jump to content

Still Get Positive Combined Chlorine After Shock?


phishfood

Recommended Posts

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??

Link to comment
Share on other sites

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)?

Link to comment
Share on other sites

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).

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...