First-time SLAM with unexpected CC and pH

[JamesW]

Also, check the TA.

 

[reggiehammond]

Just to chime in - the copper stains will likely return if you don’t rid yourself of the contaminated water. Several people have mentioned that but it seems to be ignored.

The sequestering agents work miracles, until they wear off, then you’re back at square one. While the copper is still bound up; get rid of it once and for all.

 

[mbender71]

Just to chime in - the copper stains will likely return if you don’t rid yourself of the contaminated water. Several people have mentioned that but it seems to be ignored.

The sequestering agents work miracles, until they wear off, then you’re back at square one. While the copper is still bound up; get rid of it once and for all.

Good morning! Thank you for bringing up that very important point. Jack's Magic support did let me know that I will have to continue to use their Purple Stuff regularly to keep the copper in suspension. In addition, other members here, including yourself, are definitely having me consider a continuous water exchange. I'm going to have to do my research on the TFP forums (and pool school) to learn the best way to execute that in the near future. Thank you again!

 

[mbender71]

It’s difficult to determine exactly when the sulfamic will break down.

When it happens, the pH and TA will suddenly begin to drop and the CC will go away.

Good morning! I just performed my next morning OCLT, and the results are in. Spoiler alert -> @JamesW prediction of pH and Alkalinity drop was spot on :

FC: 4
CC: 35
TC: 39
Water Temp: 74F

ph: 7.70 (before) -> 7.15 (after)
Alkalinity: 70 (before) -> 60 (after)

Here is my take on the results. The FC and CC did *not* drop at all overnight. I believe this is further evidence that the pool is void of any living organisms. This morning's reading also hints that only the sun reduces my FC and CC (mainly). The water is as clear as I've ever seen after owning this pool for 1.5 years (keep in mind, I only started maintaining it myself the past 2.5 months). Now for the prophecy mentioned by @JamesW. The pH dropped from 7.70 to 7.15 in the last 24 hours, and the alkalinity dropped from 70 to 60 in the same period. This large change in pH + alkalinity, along with a rapid drop yesterday in CC, appears to adhere to @JamesW explanation of what happens during sulfamic breakdown.

I'm going to turn on my SWG today to maintain my FC at this time (my SWG has been off since the start of the SLAM). I will also add baking soda to bring my alkalinity back up to 70. As for pH, I'm going to let it drift up naturally (I have fountain jets that aerate plenty) instead of using borax. As always, thanks to everyone for the *amazing* education and any future tips and suggestions at this time!

 

[JoyfulNoise]

Chlorosulfamates are very stable in the pH range between 4 and 11. This is due to the fact that the N-S bond is not easily attacked. When the pH is low, acid-catalysed hydrolysis attacks the S-N bond. At very high pH, the chlorosulfamates react with free sulfamate to form sulfates, nitrogen gas, and chlorides. There is a good deal of literature in this area as chlorosulfamates were investigated for many years as "safe" bleaching compounds as well as biological control agents for water systems (boilers, condensers, etc).

Given the lower stability of dichlorosulfamate at high pH, it may be advantageous to run your SWG at a higher output since the pH near the plates of the cell while generating chlorine can get quite high as long as there is no buffering agents around (borates). The higher pH may help to reduce the sulfamate faster. Obviously one couldn't increase the pH of the entire pool as that would cause scaling all over, but using the cell to do this might help to speed things along.