Has anyone else heard of this? In some AFO classes, put on by some Cal Hypo dealers, the recommendation is to raise hardness levels to maintain a hardness-alkalinity ratio of 4:1 to 6:1 or even 10:1. This is not part of the course, but was more an offshoot discussion of balancing pools, and what index is best used – the LSI, or the Rhyzner. Many instructors often put in their own tips to help keep the class interesting, but this one just got me confused.
Let me explain, and in order to get this right, I’ll quote from what one instructor/dealer told me, “These ratios act as a catalyst for efficient CO2 use, and for stabilizing both the Alkalinity and Calcium Hardness levels. The vehicle for the carbonate ion is to ride on the calcium. Not enough calcium, and the CO2 just off-gasses more readily.”
When asked about any details on the chemical basis of the theory, nothing is given except that it was found by some long forgotten chemist, whose name they can’t remember but who figured this out.
Sounds plausible, except for a few red flags that pop up here and there.Granted, calcium plays an important role in pool chemistry and in balance equations. And I’m not against going slightly beyond recommended ideal limits for calcium of 200 to 400 PPM’s, as long as you compensate for it by lowering the pH and alkalinity. And I do know of some pools that claim that the magical number for them, for calcium hardness, seems to be around 500 PPM. They say it seems to lower their acid use and evens out the alkalinity…. so I’m not discounting it, but am wondering if it coincidental with something else happening in the pool. In fact, I myself prefer to start out at 500 PPM’s, as I like to run lower alkalinity spans of 60 to 75 PPM’s to help with aqueous CO2 off-gassing. The ratios of 4:1 to 6:1 isn’t all that outlandish, as many pools will still be under 500 PPM’s of calcium using those ratios.
It’s just that higher ratio’s, which were inferred to in that discussion, of being well over 500 PPM’s that bothers me, and makes me wonder if this could all be part of their sale pitch of “High Calcium Chemistry”…in that Cal Hypo is good, and liquid chlorine is bad mentality. There is enough chemistry out there that shows that Aqueous CO2 off gasses more so in a direct relationship with low pH, and with the rise in alkalinity, temperature, and aeration. Basically, higher pH and lower alkalinity levels will help in lessoning CO2 off gassing, and thus would have an effect of stabilizing the pH somewhat. I just don’t see where “High” Calcium levels above normal recommended ranges has to play in the role of efficient CO2 use, and stabilization of both alkalinity and calcium levels.
I would just like to hear of someone who can explain some of the chemistry behind this “magical” relevance of high calcium levels as being a necessary carrier molecule for this, or that very high levels are required or even beneficial. If there really is a relevance, then what is the minimum, or guidelines for this to occur?
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Sorry for the delay in responding...
Al, you are correct, the dulling of the pool surfaces is actually a residue from the tablet itself...
I have been doing some filter maintennance on some pulsar pools, and have been findiing LARGE quantities of this muddy substance that has turned up to be the tablets themselves. its the same color as the pulsar tabs, and its a real PAIN to pull out. I had 2 spas using pulsar for 2 years, and they were practically SATURATED with this stuff. I told them to compalin to their pulsar dealer, who to this date is still scratching thier heads, and now the client is asking for them to pay for the cost of repairing the filters. BTW, their spa's look so much better now, but they are beginning to see this buildup occur again, after just 5 months... Im trying to swing them back to bleach... kind of funny, since I was the one who sold them their first pulsar system about 11 yeas ago (for their main pool)...
As for your other comment on CO2 offgassing... I wouldnt keep the ph higher that 7.4, because calcium carbonate precipitates above 7.4, and that would just create a "chalk machine" in the pool. 7.2-7.4, with corresponding pool balance parameters to maintain a +0.4 LSI has done the trick for me (at least in my neck of the woods)... NY has both well and reservoir systems depending on the location, and has been known to be a very CO2 friendly location. If your fill water has high Alk levels, you might not want to encourage co2 use there, as Cal carbonate precipitation is an issue you will be challenged with.
Always a pleasure....
Clemente,
Thanks for adding some more input to this post, as I thought this post had pretty much run its course. I’m glad it’s not.
I ‘m wondering though if what you saw in your pool is the same thing I’m seeing with Cal Hypo pools relating to my “pet peeve”. Was this pool you mentioned a Cal Hypo pool, and/or was the Calcium just being added for start up? What calcium levels were being maintained in this pool, as I don’t know if the figures you gave of 60 TA, and 240 Cal were for this pool? Was the gray film throughout the whole pool, or more or less in one area? I was just wondering if they dumped the calcium flake all in one spot.
The reason why I ask is we typically run pools on bleach that we maintain at around 60-70 TA, and add Calcium to start out at about 500 PPM’s. When the pool drops down to about 400 PPM’s, we add more Calcium Flake. We keep the calcium levels this high primarily for balance, as the TA is kept low to help reduce CO2 off-gassing.
We don’t see the grayish film on the lane markers with these pools, so wasn’t really contributing this phenomenon to just moderately high levels of calcium. My observations are leading me to wonder if this dulling of the racing line tiles is happening as a cause and effect of using the Pulsar Cal Hypo in their proprietary feeders, along with floor inlets…as this seems to be a regular happening in almost all of these pools It’s very gradual, but over time is having a noticeable effect on the appearance of the pool. It may just be a combination of calcium and binders don’t know. It’s a dulling film that isn’t like the typical scale, in that it doesn’t get very thick or sharp. When acid washed, it takes some off, but there is still a definitive dullness that takes time to remove. It’s not an issue of water clarity, as the water itself is very clear. Most operators don’t even realize it, as they come accustomed to it everyday. (The vast majority of Cal hypo Pools in our area is Pulsar, so I can’t say whether or not PPG Cal Hypo has the same effect on the tile lines.)
If you really want to see what I’m talking about with the dullness is to take a look at some back issues of Aquatics International Best Pools Series. The dullness I’m seeing is similar to some of the pics used to show off some of the “Best of the Best”. The differences in vibrancy of the racing lines are quite evident in some pools. I have no idea what sanitation system was used for the various pools, but either the pictures were taken after the pool was heavily used, or what? I’m sure the honors for these pools are well deserved, but it makes me wonder why some of those pictures were chosen to showcase the best.
Anyway, do you really recommend running dissolved calcium flake through the skimmers? Why run that high a concentration through the pump, filters, heater, etc. I just slowly walk around the pool with an open bag and slowly pour it in. Dow Flake is dissolved before it hits the bottom.
Is this a catch phrase of High Calcium Chemistry that you are repeating, or is this still something you actually believe in? Are they trying to mask the effect of High Calcium of 600,700, 800 PPM’s as being a good thing vs it being the potential trade off it really is?
For the sake of argument, why do you have to have 600, 700, 800 PPM’s of calcium in the pool? (This is what the inference was with the 4:1 to 6:1…to 10:1 or greater was referring to in those AFO Classes). As I stated in the original post, I never had an issue with 4:1 or even 6:1 as being a problem with balance, as most pools would as most pools would still be under 500 PPM’s, which is a little high, but not that high. The question was with it being relevant to effective CO2 usage as being a requirement.
Look, we both know that there are many trade off issues associated with using Cal Hypo, as there are with any technology. It’s ultimately up to the facility to determine what trade off’s are acceptable to them, and which ones are not. For them to do that, they have to know what they are. It should be up to us, as pool professionals, to OBJECTIVELY tell our customers the pros and cons of a specific product…something that is often lacking in many presentations. Many operators of large Class A pools are very knowledgeable, and crave this information from those they have learned to trust as being experts and in the know. It’s an unfortunate reality that this objectivity is often lacking.
And that’s where the gist of my questions lie…in figuring out for myself, what is fact, and what is not; what makes sense, and what really doesn’t. It’s a journey oftened riddle with ½ truths and over exaggerations.
This is absolutely true and for commercial/public pools typically with high bather loads it makes a lot of sense. However, the reality for many residential low bather load pools is that the SWG system isn't oversized very much. Also, a point is being missed here that there is a significant downside to using a lower CYA level (by sizing up the SWG system though by itself there's nothing wrong with over-sizing the SWG)l. The result is that there is more Free Chlorine (FC) produced per day because there is more degraded by the UV in sunlight. Part of the pH rise found in many SWG pools is related to the amount of SWG on-time and more specifically to the amount of FC produced. It is unclear how much of this is due to increased aeration and how much is due to undissolved chlorine gas outgassing, but the correlation is very clear. If one can lower the SWG on-time, then one can reduce the rate of pH rise. Having the CYA be higher helps accomplish that for pools exposed to direct sunlight.
There are hundreds of SWG pool owners that have achieved much greater pH stability through this technique of higher CYA even in pools where they had SWG systems that were large enough to keep up with higher daily FC usage at lower CYA levels. When they raised the CYA, they were able to lower the on-time and that lowered the rate of pH rise. Note that they had to use a higher FC target level to keep the FC/CYA ratio constant to prevent algae growth, so the minimum FC was 4 ppm when the CYA was 80 ppm, but the net FC loss per day from sunlight was lower in spite of the higher absolute FC level, most likely due to CYA shielding effects limiting UV at lower depths (along with some imperfect surface circulation). Lowering the TA level to reduce carbon dioxide outgassing also helps. The use of 50 ppm Borates is something else that sometimes, but not always, helps, partly by being an additional pH buffer (though technically that slows the rate of rise, but not the amount of acid that needs to be added) and partly by being an algaecide that inhibits nascent algae growth to further reduce chlorine demand (though that's mostly if the FC/CYA level is kept low).
Oops - Forgot to reply to ORP/CYA values...
ORP measures REDOX potential...in layman's tems...its telling us HOW well the chlorine is working in a body of water.
Since adding CYA lowers the ORP - its simply telling us that The chlorine's ability to WORK is being comprimised.
My suggestion for setting a pool to a 20ppm CYA is simply a suggestion to getting the best benefit of the CYA, which is to offset the loss of chlorine from UV light from the sun.
To maintain an 80 ppm for a chlorine generation system is simply hiding the fact that your generator isnt big enough to properly sanitize a pool (a COMMON problem in Pools that use this technology). Try adding more cells, and call it a day.
10ppm chlorine wthin one hour feeder sizing will reduce the need for CYA in the first place (my clients in Puerto Rico who have ELIMINATED CYA use by following my guidelines will attest to that).
If you have any questions, please...fel free to contact me, as I am always open to any thoughts and suggestions that will improve the industry.
Hi:
Been a while since I last posted here, and I'll be brief:
The faded blue that Al has mentioned in his post (his pet peve) is in fact that thin scale that High calcium chemistry promotes. I just went over this with a customer who's pool I just painted a few months back was complaining about. They were dumping calcium into the deep end of the pool, and over time, this greyish film was seen over the lane markers (they were black). I simply took my Jandy acid cleaner, and sent a spot wash of very mild acid to an area to prove my point - the spot was black again. I simply explained that this was human error, and that in the future, they needed to add a calcium dilution through the skimmers. I corrected their chemistry a bit, and ordered brushing of the pool over a month or so, and the problem was fixed.
High Calcium Chemistry was devised to simply change the operator's perception of scale, by helping them create a different TYPE of scale.
The 4:1 ratio is valid ONLY when the rules are followed...LOW ALKALINITY, high calcium = good water.
60ppm ALK, 240 CH, is not so bad for a pool. Its almost just right (I'd like seeing that pool around 350ppm calcium).
I think this ratio was simply devised by a Cal Hypo dealer to simplify a CPO's operations. How it became mainstream as valid fact is simply what Al mentioned...A large, respected corporation's attempt to get more customers by passing on what "seems" to work for its dealers.
Lets keep it simple. Follow your training...Follow your guidelines, whether balancing by LSI or Ryznar, and making sure that the pool is safe to swim in, at the least expense. We all have different ways of working out our issues, mainly because of where we ARE LOCATED. Water in NY is very different from water in AZ, CA, and even NJ. When I get called into a different region to troubleshoot a problem, I have to spend at least 4 hours researching the water tables there even before I get on a plane...
I agree, these ratios are just smoke and mirrors for cal hypo dealers to try to make their pools shine. As I have always maintained, I can make any pool look just as good, by maintaining the parameters that I have been comfortable with for many years. If you have a particular issue that needs attention, I would be more than happy to lend a hand. Pools are an ENTERTAINMENT business...and its our jobs to make them look their best, and keep them SAFE, PERIOD.
Drop me a line ANYTIME.
Al appropriately questioned the benefits (as claimed by some chemical dealers) of maintaining a fixed ratio of CH to TA, such as 4:1. When considering the LSI, it makes no sense to establish a fixed CH/TA ratio. When the CH is high, it is obvious that the pH and TA needs to be lowered to offset the high CH, which would result in a change to the ratio.
I believe there can be some benefits in learning how to maintain High Calcium levels in swimming pools. I have been successful doing that in my hard tap water area. But I don’t agree that a thin layer of scale in pools is desirable. Discoloration and roughness can result and the pool owner will complain. It seems to me that the promoters of a High Calcium Chemistry program would be better off recommending lower pH and TA readings, not higher, as fixed ratios would dictate.
In regards to the claim that high CH levels results in a more efficient CO2 use and stabilizes TA and CH, I am not aware of any chemistry rationale for that. As Al correctly stated in his post, CO2 off-gassing is affected by the amount of TA, the pH, temperature, air to water-surface ratio, aeration, etc., not by the amount of calcium, low or high. Richard also discussed this in his comments.
Everyone knows that adding Cal Hypo to water adds calcium. It also adds a small amount of TA and increases the pH slightly. This is due to small amounts of hydroxide and carbonate that Cal Hypo contains. Therefore, adding Cal Hypo reduces the amount of CO2 in the water. It does not stabilize CO2 or reduce the amount needed for pH control, nor does it stabilize the TA.
As for maintaining a very high CH, adding more Cal Hypo can precipitate calcium. Maybe the claim is that there will be no net increase of CH, and therefore is “stabilized?”
But don’t get me wrong, I use Cal Hypo all the time in my soft tap water area.
Note also the discussion about the Ryznar index which was developed mainly to account for the fact that when the pH was high (above 8.6), then even a high Langelier index (even +1.0) would not always result in a calcium carbonate film so the Ryznar index empirically took that into account. Remember that the Langelier index is not a corrosion index nor does it predict if scaling WILL occur, but rather whether scaling CAN occur. If the index is negative (accounting for actual temperature in the region of interest), then scaling cannot occur.
At pool pH, the LSI/CSI indices are reasonable, certainly for the minimum water chemistry values needed to saturate the water with calcium carbonate (i.e. for even the possibility of forming scale). As for whether there will be significant scale buildup more than just a thin film, the Calcium Carbonate Precipitation Potential (CCPP) can be calculated. You can use my spreadsheet to calculate CCPP when you set the Initial values result in a positive CSI. You then enter and adjust a negative value under "Dissolving CaCO3 (neg. for scaling)" to make the Goal CSI zero and that number you enter that achieves this is the CCPP in ppm CaCO3 (I may add a button to do this automatically at some point). The CCPP captures what Ryznar was trying to predict, but does so using real science (it was too hard to calculate by hand in those days). Water systems (see this link) target 2-5 ppm for CCPP to prevent too much scaling while still providing over-saturation to have corrosion protection. My water district, however, has water with a TA of 80, CH of 50, and pH of 7.8 to 8.0 so is not saturated so they add 400 ppb phosphates as a corrosion inhibitor.
Let's use some real numbers to see what happens. Let's say you use 1000 ppm CH with 100 ppm TA and a pH of 7.5 at 85ºF temp. The CSI is about +0.5 so scaling COULD occur. The CCPP is about 15 ppm which is on the high side so could produce more scale than one would want. However, we didn't use the temperature at the heat exchanger and if I add 30ºF to the temp I get a CSI of +0.7 and a CCPP of 18 ppm. If the heater is even hotter, then there is even more scale potential. If you repeat this analysis, but get the TA down to 50 ppm, the CSI becomes about +0.3 in the bulk pool water while the CCPP becomes about 4 ppm which is reasonable, though the 50 ppm TA means the pH buffering will be lower (but the rate of pH rise from carbon dioxide outgassing will also be much lower).
So there isn't really anything inherently wrong with high CH by itself, but if the TA or pH aren't targeted lower then you can get more scaling than you'd want. Is there an actual table of recommended CH/TA/pH combinations that the high calcium chemistry folks recommend? That would go a long way in seeing if their recommendations have, for example, reasonably consistent CCPP values. For the thin-film corrosion protection, I see no reason to have visible scaling on bulk water pool surfaces -- that just seems to be "too high" in over-saturation.
As for ORP and CYA effects on chlorine effectiveness, etc., high bather load pools need supplemental oxidation, period. Whether that's from non-chlorine shock (MPS), enzymes, or from ozone or partial assistance from UV (for chloramines), you need something other than chlorine alone to oxidize bather waste quickly enough without producing excessive "bad" chloramines (such as nitrogen trichloride) and the THMs. I know that Kent Williams at PPOA touts the high chlorine without CYA (so high ORP) approach and while there is no question that it will oxidize bather waste faster, it does so with more side effects. My comments in other posts about using CYA even in indoor pools, for example, presume that one uses supplemental oxidation to handle bather load (and for indoor pools having UV to make up for the lack of sunlight that helps keep some chloramines in check). A lot of the science about this is still in its infancy since it was only in October of this year that Dr. Blatchley published new information on the oxidation of urea (see this paper which unfortunately is not free) which is the largest nitrogenous component of sweat and urine.
By the way, the post with the graphs of ORP vs. FC and ORP vs. calculated HOCl are based on commercial/public pools, not residential pools. I really don't like ORP as any sort of absolute measure given the variability among sensors/manufacturers, but you are right that you can use it for process control using a setpoint.
Heater manufacturers will really try to get you to pay attention to the internal bypasses, or in some cases the temperature differential through the heater. This is because when water gets to 115F - 120F it starts to push everything out of solution, right onto the exchanger, and hence it plugs. So they want it regulated to stay below there. Bad flow, bad bypasses etc will create scaling conditions within the heater.
This is also why I rant on about using High Efficiency Frame & Plate exchangers on Pools. For Hydronics they load the water with chemicals to make everything stay in solution but in pools? We have to use good chemistry and common sense to prevent scaling. We also throw in threads and band aids and hair that all get caught in the little capillaries and plug said High E. exchanger forcing higher head losses throughout the system and causing other issues. Stay with Shell & Tube!
Richard,...all I can say is wow...and Clemente, thanks for participating in this. I was hoping to get your perspective on this. For those that don’t know your long history with Cal Hypo, I’ll just clue them in on that you were a PPG in Puerto Rico, and later a Pulsar dealer when you moved to New York. So I hope your input will spur more debate on this issue. The reason why I know this about Clemente, is that he and I have had some interesting conversations in the past, about Cal Hypo and about High Capacity Feed liquid chlorine systems, of which I am a dealer for, and I think that he is trying to become one if not already.
He has a rather unique inside perspective on the mindset on how some of the core network of proprietary pulsar dealers, actually approach the commercial market. You have to remember that these are very hardworking, very influential, very controlling, and sometimes very large companies that are that have rightfully gained the respect of the pool industry, and thus are trusted, and believed at face value to know what they are all talking about. These dealers are a very tight group, and are very protective of their sales of tablets, which for them is a very profitable part of there business. And I’m o.K. with that…as I would be o.K. with the so called benefits of High Calcium Chemistry if…and this is a big IF…they could/would explain why most of the benefits are riddled by generalities and inconsistency in their explanations on why something is so. Everything sounds good, until you think about it and say… what?
I admit, I’m out my league on this, and been trying on my own to figure this ratio question out, only to come up with more questions. I need the help of someone like Richard, and Kim, and hopefully others to pin some of these generalities down…to see if there is any real basis behind some of what they say has enough truth behind it to be valid and to be beneficial to us all. If it is, then as Clemente said, you can always buy calcium flake instead of tab’s, and still reap the benefits of High Calcium, and do it a lot cheaper than using tab’s.
So, let’s get back to Clemente’s post, which at first sounds reasonable. I see that Richard already commented on most of it, and I see where he started seeing some of the inconsistencies. Richard mentions the heat exchanger argument for the Rhyzner, If Pulsar pools have a powdery coating of calcium carbonate on pool surfaces, then that implies a positive calcite saturation index in the bulk pool water, but in a heat exchanger which has much higher temperatures that would encourage scale formation. So that's inconsistent. If one targets a saturation index that over-saturates the water to form a film in the bulk pool water, then it will form even thicker scale in the heat exchanger that is much hotter. So much of this High Calcium Chemistry stuff hits you later and you start to think…what???
Let’s talk a little more about his thin “GOOD” scale. Yes, I would agree that a thin film might be beneficial, particularly in the heat exchanger, or in impeller / volutes areas of many large pumps. This maybe flippant, but in some of my google searches on trying to find something out on the Rhyzner, I’ve heard about arguments that it’s possible to have more issues with failures due to pinholes in the film, which concentrates a flow of water, at bends perhaps, to a very small area causing a leak. Sounds iffy I admit, but maybe possible.
Other than Richards’s argument with a greater scale build-up in the exchanger, I‘ll focus on this light, rather unnoticeable build-up on the pool shell, as it’s starting to be a pet peeve of mine.. Maybe some of you can help out and verify this for me in your areas. One of the things I’ve noticed on a lot of cal hypo pools is this, and it comes as a trade-off of perpetuating High Calcium Chemistry. The criterion is that the pools have been using Cal Hypo for some time. Now one of the benefits of Cal Hypo is that it makes the water very pretty, and very clear. I would say that this is true…initially, but then something else happens…and it has nothing to so with clarity, but more so with vibrancy. Almost every pool is very clear, meaning that you can see the grout tile lines in 10 ft of water. Yet most pools that have blue racing lines that have lost their deep blue colors. There faded, lighter in color…almost looking hazy. Most operators don’t realize it because it’s so gradual…but when you compare it to other pools, it’s there. The trade-off with this light “GOOD” scale build-up, along with the inert binder material from the tablets that is supposed to be beneficial. The gunk that is clogging up the feeders is being flushed onto the pool, and what doesn’t build up on the pool shell is effectually caught up in the filters, which brings up another interesting trade-off. Filter calcifications, and insufficient backwashes that end up clouding up the pool with a whitish cloud after every backwash. Many sand filters, after 4-5 years on Cal hypo experience a clouding issue after backwashing. Unless you’re doing a very heavy backwash each and every time, the filter eventually builds up enough to a point to eventually puts some of it back into the pool. Those of you on the expensive regenerative filters often have to deal with the socks scaling up. A few trade-offs they don’t tell you about. It’s happening in enough pools to make it a concern, but not many people know what or why it’s happening.
Clemente mentioned that US filter introduced the Rhyzner Index to the pool industry. Actually this was before their short-lived marriage with Arch Chemicals. Their reason may have been to protect the Heat Exchanger. This may be a reason that they promote, but it’s probably not the main reason. There’s another reason that he didn’t mention, but is believed to be just as true.
Remember the network of proprietary Pulsar dealers mentioned above. Well, those same dealers are also the proprietary network of US Filter / Stranco dealers. Like I said, this group is very influential. The Pulsar dealers knew that they had an issue with rising calcium levels with the use of Cal Hypo, and noticed that the LSI didn’t work so well when it came to high calcium levels, as I suppose their ORP controllers due to the bar scenario that Clemente gives. Who knows? So, the way the story goes, is that a Research Dept Head from US Filter went out and found an index that allowed for higher calcium levels, and the network promoted it as a better index for corrosion. Its benefit was that it would balance out at high Calcium Levels. Convenient, isn’t it. It was this influential network that made it possible. Was it right to do…is it beneficial…or is it just a marketing ploy encompassed under the banner of High Calcium Chemistry?
Does it work? Enough pools seem to think so…but is it because of the index, or because of lower alkalinities and lower pH? Is it confusing to use…yea, considering there are no (-) numbers, and scaling is related to the lower numbers, and corrosion is to the higher numbers. It was only when programs came out that compared side by side, the LSI with the Rhyzner, that it became apparent that most scenarios under 0.4 were very confusing at best. Many scenarios put the LSI at scaling, and the Rhyzner being very corrosive. The “sweet spot” when both index’s would be in somewhat of a balance at the same time was when the LSI at a +0.4 or greater. The LSI is more reactive at lower settings, and with pH and temperature being the most influencing factors. Calcium has little effect between 500 to 999 PPM’s. Personally, I like the corrected LSI that JSPI put out a few years back.
Clemente mentioned this is his post, and I would like a little further discussiojn on wht is meant by created enviroment, and if it has anything to do with the ratios of calcium to alkalinity. “Arch will also tell you that Cal hypo is a better fit for CO2 use, because the environment created by the product (water balance wise) is more beneficial for CO2 use. This is debatable;”. Clemente never did address the initial question of ratios, and what that was all about. Now I’m not sure if Richard answered this in his responce to Clemente, as Richard can be overwelming, and my head hurts a little too. Bit Clemente, please elaborate. I don’t understand how the high TA fill water spikes you mentioned has to do with the calcium enviroment mentioned above.
On to ORP and cyanuric acid, and TDS I guess. It’s getting late, so I’ll make this really short. I hope we don’t get into a discussion on this topic, in this thread, as I would really like this to stay with the topic of High Calcium Chemistry, which includes the Rhyzner, but not this.
Anyway, briefly, and I’m pretty much going off the top of my head here as I’m very tired. I’m a firm believer in High ORP’s, above 810 mV at relatively low levels of free chlorine, around 2 PPM’s, at a 7.45 pH (yes 2 decimal places).
ORP measures the oxidation potential of everything in the water. For chlorine, it’s the HOCL, and it literally doesn’t matter what the tested free chlorine is. You could have 800 mV at 30 parts free chlorine, and you can have 800 mV at 1 part free chlorine. It’s all dependent on pH, amount of cyanuric acid, temperature, and somewhat TDS, all of which lowers the ORP.
So when Clemente says that it is a good thing that High Calcium increases TDS and makes the transfer (bar scenario) is saying that the ORP is lower and that’s a good thing…NOT.
When Richard says in his reference citing, that cyanuric acid lowers the activity of chlorine, and that less chloramines develop because of the lower activity, then I say sure, but not in a commercial pool. The graph he references is clear on that cyanuric acid lowers activity even though you are showing more than enough free chlorine on the test. Sanitation is about keeping up with demand, and you are not going to do that with small feeders, with cyanuric acid that’s lowering the availability and/or speed of the reaction, or with high TDS that gets in the way of the reaction. If the ORP is getting lower, and your not keeping up to keep it higher, then you’re simply defeating the purpose. You just can’t use scenarios for residential pools that are relatively low demand, and have the time to deal with low speed reactions caused by cyanuric acid, and expect to compare them with meeting hi demand commercial pools that are governed by codes, which is why I suspect, you are hitting a brick wall with the NSPF on the CPO issue. The chlorine chemistry may be the same, but the time frame for it to occur isn’t. It’s why salt generators manufacturers promote high levels of cyanuric, because it is a way they can at least get a free chlorine reading, because it simply has difficulty in keeping up with the demand in a timely fashion when used in many commercial pool scenarios – the key words here are timely fashion. It’s also why in our State, that if you have a salt generator, no matter how big you size it, then you also have to have a secondary chlorine system.
As for the sensors, and the differences in meter readings; yes that’s true. But for many hi end controllers, and I mean the Bec’s, The Stranco’s, The Accutrols, and maybe the some of the Chemtrol’s, the readings are fairly stable for that unit and for that sensor, over the life of that sensor. Will 2 controllers read the same? No. But for a given body of water, that has the same controller on it, it will give a representation of HOCL activity via set points. In my experience, Bec’s and Strantrol units are the best out there right now, and Cat sensors are frustrating, because as they get older, they change their outputs. I can start out at 820 m/V, and 2 years later be at 650. When it’s at 650, I can change out the sensor, and get an immediate 820 mV on the same body of water. Has nothing to do with the water quality…just the sensor. It’s the only sensor I’ve found that consistently does that.
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