Have been using the sequestrant/chelator Jack's Magic "The Magenta Stuff", and the usage to maintain a level of 20 ppm has been very high. This after doing the Jacks "Iron and Scale Treatment” now completed, during that treatment it used significant amounts of "The Magenta Stuff". It worked very well chelating significant amounts of metals out to the filter, no iron is visibly present.
I initially thought that I was actually using less but I went back to my notes and noticed that I actually put in 40 oz after refilling the pool and not 20oz; I did it twice on the same day. Then checked the next day and because it showed 20 ppm I thought all was fine, the next day the level was at 2 ppm, added 18 ppm, and again the next day again it went back to near 0 ppm.
I "Goggled" HEDP and loss and degradation, and found that HEDP while not affected greatly by chlorine or pH, was subject to significant photodegradation due to sunlight if the water has metals in it, especially if combined with iron and possibly copper. If you "Google" typing "HEDP Photodegredation", there are many discussions on the subject. Obviously it does not affect boiler treatment as no sunlight enters the cylinders. I am not stating that this is the reason but it seems a reasonable explanation as to why the sequestrant HEDP is being used up so quickly. If you think, or know any other reason could you please advise your thoughts.
Today I raised my CyA to 60 from 25, normally I keep it at 30, to see if this will offset the effect of sunlight as I cannot afford to keep putting in this much sequestrant. I will have to see if that works.
Question, my main issue right now is mild copper staining, if you read the articles shown by Google are they saying that during the photodegredation process the iron, and perhaps copper, are the released into the air? As I am no chemist I cannot understand exactly what is happening during this process.
I think the reason that some people are posting that even though they have added the sequestrant the water becomes colored again showing signs of iron or copper in it, this may be due to the fact that the sequestrant is being quickly used up during the photodegradation process, as effectively there is only 0.002% sequestrant in the water at 20 ppm. If this is so, and if the CyA is low at 30 ppm I think, but do not know, that photodegradation is taking place at a rapid rate causing the HEDP levels to drop to 0 ppm very quickly, thereby causing this coloration.
I hope that raising the CyA to 60 ppm will solve the issue and will advise if it does.
Question, if one is trying to get rid of copper staining faster might it be better to leave it at 30 ppm with the apparent photodegradation in place? I personally do not think so but would like a more scientific opinion.
Once the In-Pool Acid Treatment is over the new target figures will look as follows, I changed from my previous target figures due to increased CyA:
pH 7.6 - 7.7
FC 4.5 - 5
Calcium Hardness 400
Temp 78 - 83 (Avg. 80)
CSI -0.15 to -0.05
Any comments or help would be appreciated.