Higher PH level makes my water more prone to develop Chloramines?

[lesandov]

Hi everybody!

Two weeks ago I had a terrible issue with a high CC level on my swimming school. My main instructor and some of the students got a rash problem. The CC Level got up to 1.5 ppm. Last weekend I decided to SLAM the pool raising the FC level to 20 and hold it all the way through friday night to monday morning. I manage to low the CC level to a safest <0.5 ppm. No more complaints about skin conditions so far.

Since this is a totally Indoor Pool, with a rather low CYA level of 20, and no sunlight touches the water surface, I understand that keeping CC is a challenge. I consulted the guy at my local pool store about this issue, and he stated that, since I was using just bleach as a sanitizer, the usually high pH levels (7.7 - 7.9) in my water will produce higher levels of CC. Thus, I decided to add .5 to 1 lt of muriatic acid everyday to keep pH level between 7.2 and 7.6. TA has been consistent at 80ppm for the last three months, but I expect that to lower due to the muriatic acid action. Also the pool technician recommended the use of a non-chlorine shock product (ozone based) in a weekly basis to get rid of the chloramines in a four-hour period. This is a rather expensive course of action and I am not sure this is the best for my pool.

Also I was reading that Chloramines when given off from a pool in the form of a gas will redissolve in the pool unless removed by an efficient ventilation system. So, I decided to keep all the shades and windows open in the building to give some more fresh air inside and around the water area. I use a cover over the pool every night after regular class schedule to keep the water warmer, but now I am concerned that this will interfere with organic compounds oxidation which will aggravate the matter.

Would anyone like to elaborate on these?:

1) High pH levels will increase the chances of getting higher CC levels?
2) Getting a better ventilation in the pool area and perhaps not using a cover will help to keep CC rather low?
3) What other actions can be taken to prevent CC level scalating?

Thanks in advance

Luis

P.S. I found this information illustrating.(Controlling Chloramines in Indoor Swimming Pools)

 

[Texas Splash]

Hello Luis. Your situation will probably prompt more replies from experts, but a few comments I have for now are:
- Your high CC reading required a SLAM, but you didn't appear to do the SLAM long enough to truly kill what was causing it. By that I mean you didn't state that you passed the 3 SLAM criteria. So be careful in that the CC level may rise quickly again if that's the case.
- I don't believe the pH level has anything to do specifically with the CC results you are receiving. That's a sanitation/oxidation problem.
- When you performed your short SLAM over the weekend, you took it to a much higher level than required based on a CYA of 20. Your SLAM level is only an FC of 10. But again, it needs to be held there until you pass all 3 SLAM criteria (link below in my sig).
- If anything, I would think the cover would have a negative effect, preventing CC from escaping the water source.
- Keep in mind too that Potassium monopersulfate (a common non-chlorine shock) will show up on FAS-DPD chlorine tests as CC. Not sure you ever used that type of product, but there is a special reagent you can get to neutralize the potassium monopersulfate so you can get a true CC reading.
- Future CC control is typically a matter of ensuring the FC/CYA ratio are maintained properly and consistently throughout the day. Higher bather loads will certainly disrupt that normal FC balance in your pool and require special attention.

Those are some initial thoughts to help get this thread going. Others may have more advice. But the one thing I would highlight in any case is that when the CC level gets too high, a SLAM is probably in order and it has to be maintained until all 3 SLAM criteria are passed. Best of luck to you. Have a nice weekend.