Dust Posted March 31, 2009 Report Share Posted March 31, 2009 Hi All Sorry for more topics in here about salt generators... I know its not very useful to a lot of you; but to those of us who have them, its invaluable to get this info, because its so hard to find it anywhere else. Anyhoo, my question is about buffering chlorine in a salt generator system. Specificaly with the Onzen system, we run with a true zero CYA content... and these generators have no problem sneaking up to 4,5,6 even 10+ ppm FC. Because its not buffered, our FC levels can fluctuate quite a bit over time... if you want any residule FC for even 4 people and a mini hottub party (4 people x 1hour use @ 103F) you can easily deplete 6-10 ppm FC depending on the person, so you need to keep the pre use FC levels pretty high. hah, on the flip side, my water is always breathtakingly crystal clear... you can almost here the bacteria on our skin scream in horror before we jump in the tub Of course, my wife eats through 100 dollar swim suits like nothing, and our poor little seat pillows aren't going to see thier first birthday. Dealer is useless when it comes to questions about CYA... it seems they don't even know it plays a part in balancing a tub half the time... and specificaly on a salt generator, they are pretty clueless. SOOO, in a tub with a chlorine based salt generator, ozone, and NO silver ion (since it hasn't been approved here in canada yet... at least not on the onzen systems), what would be (if any) cons of bringing in maybe 20-30ppm CYA using a CYA additive, how will that affect overall water chemistry over time, and will that interfere with the salt -> sanitizer -> salt cycle? Thanks in advance if any of you gurus out there care to take a stab at this for us Thank you!! -Dust (p.s. sorry for the mispost in the wrong location earlier... my bad) Quote Link to comment Share on other sites More sharing options...
chem geek Posted March 31, 2009 Report Share Posted March 31, 2009 Specificaly with the Onzen system, we run with a true zero CYA content... and these generators have no problem sneaking up to 4,5,6 even 10+ ppm FC. Because its not buffered, our FC levels can fluctuate quite a bit over time... if you want any residule FC for even 4 people and a mini hottub party (4 people x 1hour use @ 103F) you can easily deplete 6-10 ppm FC depending on the person, so you need to keep the pre use FC levels pretty high. hah, on the flip side, my water is always breathtakingly crystal clear... you can almost here the bacteria on our skin scream in horror before we jump in the tub Of course, my wife eats through 100 dollar swim suits like nothing, and our poor little seat pillows aren't going to see thier first birthday. : : SOOO, in a tub with a chlorine based salt generator, ozone, and NO silver ion (since it hasn't been approved here in canada yet... at least not on the onzen systems), what would be (if any) cons of bringing in maybe 20-30ppm CYA using a CYA additive, how will that affect overall water chemistry over time, and will that interfere with the salt -> sanitizer -> salt cycle? Dust, The tub is apparently not exposed to direct sunlight since without any CYA in the water the chlorine would have been broken down quickly by the UV in sunlight. My wife experiences the same thing yours does since she swims in an indoor pool over the winter and it doesn't have any CYA in it. Her swimsuit degrades (loses its elasticity) over just one winter season of use and her skin is flakier and hair more frizzy. In our own outdoor pool with CYA, her swimsuits have lasted many years with no degradation and there is far less effect on skin and hair. Having 30 ppm CYA in the water would significantly cut down the active chlorine (hypochlorous acid) concentration which is a good thing in your case since the active chlorine level is far too strong and is wearing not only on swimsuits and skin, but on tub components including the cover. The CYA moderates the active chlorine level, but other than that you won't notice any difference. CYA acts as a chlorine buffer releasing active chlorine as it gets used up. The amount of active chlorine will still be high enough to kill pathogens quickly and will still be able to oxidize bather waste though it will take a little longer so you might notice some Combined Chlorine (CC) measurement somewhat longer after a soak (say, for an hour instead of 10 minutes), but that is not a problem. There should also be a lower rate of creation of disinfection by-products, including nitrogen trichloride, and that's a good thing. Richard Quote Link to comment Share on other sites More sharing options...
Dust Posted March 31, 2009 Author Report Share Posted March 31, 2009 Excellent, thank you for the info Richard. As I said, I was just worried about how the cya somehow interacting with the whole swg cycle, so its good to know that nothing popped out at you as a big red flag. Also, from reading your other posts, my understanding is the FC level will actually stay steady under bather load longer once cya is added to the water (as it is buffering how much FC can be consumed at a time?) Now that I know adding a bit of CYA will be safe for my tub, are the following assumption correct? a) Because CYA will limit / buffer the amount of FC used for oxidization during any period of time, I will require a lower FC concentration in the water to retain a residual level of FC after prolonged usage? (i.e., it will take longer to form CC, and then longer afterwards to recover FC)? Thanks again! Chris Quote Link to comment Share on other sites More sharing options...
chem geek Posted March 31, 2009 Report Share Posted March 31, 2009 Excellent, thank you for the info Richard. As I said, I was just worried about how the cya somehow interacting with the whole swg cycle, so its good to know that nothing popped out at you as a big red flag. Also, from reading your other posts, my understanding is the FC level will actually stay steady under bather load longer once cya is added to the water (as it is buffering how much FC can be consumed at a time?) Now that I know adding a bit of CYA will be safe for my tub, are the following assumption correct? a) Because CYA will limit / buffer the amount of FC used for oxidization during any period of time, I will require a lower FC concentration in the water to retain a residual level of FC after prolonged usage? (i.e., it will take longer to form CC, and then longer afterwards to recover FC)? Thanks again! Chris No, the FC level does not exactly stay steady longer with CYA in the water. FC gets consumed with most bather waste quickly. What takes longer is complete oxidation of that bather waste so usually that will show up as some FC going to CC and hanging around a little longer as both continue to drop. The CYA doesn't change the total amount of chlorine that is available, that is the FC, but just slows down its reactivity. However, chlorine reacts with ammonia very quickly (in seconds to a minute) even with CYA in the water. It's slower to react with urea, but at hot spa temperatures should still handle that in a matter of hours, certainly long before the next soak. After FC becomes CC it then becomes nitrogen gas and escapes the spa. You don't "recover" FC. That's why you need to add more chlorine and more so with more tub usage. So the amount of FC you need is the same with or without CYA. It takes the same FC to get rid of your bather waste either way. It is possible that you may find a lower chlorine demand with some CYA in the water since there may be less chlorine outgassed from the water since the CYA should slow down that process. So maybe your FC level could be lowered, but see how things go first before making that kind of change. Richard Quote Link to comment Share on other sites More sharing options...
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