Jump to content
Sign in to follow this  
jkusmier

Recommended Cya Levels For Pool W/ Swg

Recommended Posts

I've read many threads here, as well as at troublefreepools and other sites, and ntoed w/ interest the discussions about proper CYA levels. Some recommend 30ppm, others claim that's too much, just a few ppm will do the trick. Well, I recently posted a question about whether there might be a recommend output setting for an IntelliChlor IC40 - given certain liner type, gallonage, pump size, etc. - to maintain CL at 1-3ppm The answer, which I suspected at the time I posted, was that there are simply too many variables (temperature, sunlight, pool chemistry) to recommend any kind of default setting. A Pentair rep phoned me today and said the same thing.

Of greater interest, he also said I should maintain CYA at 75-85ppm, and referred me to www.intellichlor.net, which says a CYA level of 75-85ppm is one of the three top things to know about effective use of an intellichlor.

Thoughts?

Share this post


Link to post
Share on other sites

We originally thought that the appropriate CYA level would be roughly in the 30-50 ppm range due to the "bang for your buck" protection effect of CYA since a little does provide a lot of protection of chlorine from breakdown by UV in sunlight. This graph shows that the chlorine half-life (how long it takes for half of the chlorine to break down) is mostly increased up to around 20-30 ppm with diminishing returns above that (the X-axis is logarithmic). However, some careful experiments by a pool owner here showed that there is an additional protection effect from CYA in the range of 50-80 ppm that is beyond what my graph showed. My graph was based solely on the theoretical amount of disinfecting chlorine that is unprotected vs. chlorine bound to CYA (chlorinated isocyanurates) that is protected (still breaks down, but more slowly). Apparently, there is an additional effect and we don't know for sure what it is but I suspect it's related to CYA's direct absorption of sunlight that protects lower depths in the water from the UV rays of the sun -- that is, a "shielding" effect. For this effect to show up as dramatically as it does in the experiment, the water near the surface must not be well circulated, so I'm not sure this is the correct explanation. Nevertheless, the effect is real and means that even having a proportionately higher FC with the higher CYA to keep the same disinfecting chlorine level, the higher CYA makes the chlorine last significantly longer.

So the bottom line is that having a CYA in the 60-80 ppm range (especially 70-80 ppm) shows a large protective effect. With manually dosed pools, this is a bit risky since you have to make sure you don't let the FC level drop below 7.5% of the CYA level, or around 6 ppm for 80 ppm CYA, since fighting an algae bloom at the higher CYA level requires more chlorine (around 32 ppm FC shock level). For an SWG pool, the risk is lower due to the automatic dosing and the FC level can be lower as well compared to manually dosed pools due not only to automatic chlorination that is more stable but due to super-chlorination of part of the water that passes through the SWG cell. So the minimum FC level in an SWG pool is around 4.5% of the CYA level so for 80 ppm CYA that's around 3.6 ppm. The 1-3 ppm FC is incorrect and we've seen many SWG pools at 1 ppm and 2 ppm FC and 70-80 ppm CYA develop algae.

The main reason to have the higher CYA level in an SWG pool is to lower the SWG on-time. This makes the SWG cell last longer, but also reduces the amount of aeration that causes carbon dioxide to outgas from the pool and causes the pH to rise. SWG cells produce hydrogen gas bubbles that aerate the water.

Interestingly, when we contacted virtually every manufacture of SWG system, none of them could properly explain the reason for the higher CYA level except generically that it let you lower SWG on-time (i.e. they didn't know why or they varied in their explanations). Originally I came up with a theory about CYA making the SWG cell more efficient by combining with the generated chlorine, but that is clearly not the correct explanation as the experiments showed.

Richard

Share this post


Link to post
Share on other sites
We originally thought that the appropriate CYA level would be roughly in the 30-50 ppm range due to the "bang for your buck" protection effect of CYA since a little does provide a lot of protection of chlorine from breakdown by UV in sunlight. This graph shows that the chlorine half-life (how long it takes for half of the chlorine to break down) is mostly increased up to around 20-30 ppm with diminishing returns above that (the X-axis is logarithmic). However, some careful experiments by a pool owner here showed that there is an additional protection effect from CYA in the range of 50-80 ppm that is beyond what my graph showed. My graph was based solely on the theoretical amount of disinfecting chlorine that is unprotected vs. chlorine bound to CYA (chlorinated isocyanurates) that is protected (still breaks down, but more slowly). Apparently, there is an additional effect and we don't know for sure what it is but I suspect it's related to CYA's direct absorption of sunlight that protects lower depths in the water from the UV rays of the sun -- that is, a "shielding" effect. For this effect to show up as dramatically as it does in the experiment, the water near the surface must not be well circulated, so I'm not sure this is the correct explanation. Nevertheless, the effect is real and means that even having a proportionately higher FC with the higher CYA to keep the same disinfecting chlorine level, the higher CYA makes the chlorine last significantly longer.

So the bottom line is that having a CYA in the 60-80 ppm range (especially 70-80 ppm) shows a large protective effect. With manually dosed pools, this is a bit risky since you have to make sure you don't let the FC level drop below 7.5% of the CYA level, or around 6 ppm for 80 ppm CYA, since fighting an algae bloom at the higher CYA level requires more chlorine (around 32 ppm FC shock level). For an SWG pool, the risk is lower due to the automatic dosing and the FC level can be lower as well compared to manually dosed pools due not only to automatic chlorination that is more stable but due to super-chlorination of part of the water that passes through the SWG cell. So the minimum FC level in an SWG pool is around 4.5% of the CYA level so for 80 ppm CYA that's around 3.6 ppm. The 1-3 ppm FC is incorrect and we've seen many SWG pools at 1 ppm and 2 ppm FC and 70-80 ppm CYA develop algae.

The main reason to have the higher CYA level in an SWG pool is to lower the SWG on-time. This makes the SWG cell last longer, but also reduces the amount of aeration that causes carbon dioxide to outgas from the pool and causes the pH to rise. SWG cells produce hydrogen gas bubbles that aerate the water.

Interestingly, when we contacted virtually every manufacture of SWG system, none of them could properly explain the reason for the higher CYA level except generically that it let you lower SWG on-time (i.e. they didn't know why or they varied in their explanations). Originally I came up with a theory about CYA making the SWG cell more efficient by combining with the generated chlorine, but that is clearly not the correct explanation as the experiments showed.

Richard

the reason (straight from the CPO book they tell you 30-50 is cause tri-chlor adds it and bathers remove it via swimsuits and evaporations, or leaks. to much cya leads to mustard algea pool 101

Share this post


Link to post
Share on other sites
the reason (straight from the CPO book they tell you 30-50 is cause tri-chlor adds it and bathers remove it via swimsuits and evaporations, or leaks. to much cya leads to mustard algea pool 101

Of course Trichlor adds CYA, but the CPO book doesn't tell you that the rule is that for every 10 ppm FC added by Trichlor, it also adds 6 ppm to CYA. For every 10 ppm FC added by Dichlor, it also adds 9 ppm to CYA. For every 10 ppm FC added by Cal-Hypo, it also adds 7 ppm to CH. These rules are chemical facts that are independent of concentration.

But that has nothing to do with 30-50 ppm and it certainly has nothing to do with evaporation since evaporation does not change the CYA level because the refill water has no CYA in it. CYA does not evaporate so if the water evaporates, it merely concentrates the CYA while the refill water dilutes it and you end up right back where you started. As for swimsuits, that's like splash-out and is usually not very much dilution. Backwashing filters is a much larger source of dilution especially with smaller pool volumes.

If someone has a chlorine usage of even 2 ppm FC per day and uses Trichlor as their sole source of chlorine, then that is a buildup of 36 ppm CYA per month and dilution does not reduce this very much. It doesn't take very long for a pool to get over 100 ppm. My own pool has an opaque electric safety cover so chlorine usage is lower, but in my early naive days before I researched pool water chemistry, I used Trichlor pucks/tabs in a floating feeder and with chlorine usage just under 1 ppm FC per day I had around 150 ppm CYA in a year and a half. I then had unusually high chlorine usage and was on the edge of algae growth even though I was using a PolyQuat 60 algaecide, though only every other week.

But the question was not whether 30-50 was appropriate but why the SWG manufacturers generally suggest 60-80 ppm or thereabouts and that was what we discovered via experiment that the protection from CYA was not as indicated in the traditional graph I linked to but rather had a non-linear benefit between 50 and 80 ppm. A similar version of the traditional graph is shown in this PDF file from the Professional Pool Operators of America.

And it's not too much CYA by itself that leads to algae (mustard or any other kind) but rather the ratio of FC to CYA since that approximates the actual disinfecting chlorine (hypochlorous acid) concentration. That's something else that the CPO courses don't tell you. They instead show you the following graph on the left and don't tell you that it does not apply and the true graph is on the right when chlorine is in the presence of CYA. The red line in each graph is the disinfecting chlorine (hypochlorous acid) concentration.

HOCl-OCl-noCYA.gifHOCl-OCl-30CYA.gif

The truth is that if you maintain a higher FC level when the CYA level rises then you will prevent algae growth. The experience of hundreds (probably thousands by now) of pool users and original data recommendations from Ben Powell of The Pool Forum have shown that for manually dosed pools keeping a minimum FC that is 7.5% of the CYA level will prevent algae growth (up to a phosphate level of around 3000-4000 ppb which is very high; above that you need higher chlorine levels and it's not usually worth it so a phosphate remover may be a better choice though it's expensive). As I mentioned in my previous post, SWG pools can operate at somewhat lower FC/CYA ratios. The FC/CYA ratio as an approximation to the disinfecting chlorine concentration is based on chemical equilibrium of the chlorinated isocyanurates (chlorine bound to CYA) known since 1974. Unfortunately, they don't teach this FC/CYA rule in the CPO classes, do they?

Richard

Share this post


Link to post
Share on other sites

Richard, thanks for a very informative response. You replied to an earlier post of mine, where I wondered if there was a default setting for my IntelliChlor IC40 given my gallonage, pump capacity, etc. You recommended a CYA level of 60-80ppm to minimize the on-time (hence hydrogen gas production) and keeping TA at or below 80ppm to reduce pH rise.

I hope you'll remain patient as I ask another question - can I reduce the rate of aeration due to hydrogen gas production by adjusting my return ball fittings? I've read the recommended position is 45 degrees down, but I'm trying to see the big picture here. I suspect adjusting them upward will reduce FC (insofar as new CL is going to the surface layer, where it's most succeptible to UV radiation and will hence have a shorter half-life, despite CYA) and also impact overall circulation, from both a temperature and filtering standpoint.

As an afternote, does the presence of hydrogen gas bubbles pose any potential problems besides creating a psuedo cloudy effect (visible only at night, of course)? I added some 3 lbs of CYA yesterday (based on my calculations, CYA should now be in the neighborhood of 60 - will have water tested tomorrow) and lowered my IC40 setting to 40% tonight. Goal is fairly stable water chemistry and maximum lifespan from my IC40 - but curious as to whether the hydrogen bubbles pose any other issues.

Please be easy on me, and thanks for your time.

- Joe

Share this post


Link to post
Share on other sites

Joe,

I'm sorry I didn't seem patient in my previous post. I was frustrated by the "pool 101" comment from the other poster. If the CPO courses were more thorough and complete with their information, then I'd agree that all answers would be found there, but though those courses are not bad, they are not complete and sometimes not accurate (though mostly it's missing information, not wrong information). It's a shame that pool owners have to figure out some of these things ourselves, looking up scientific papers, doing calculations, experiments, etc. Even when some part of the industry itself figures out the truth, it doesn't get widely disseminated such as this paper from The Journal of the Swimming Pool and Spa Industry (JSPSI) that debunks the "acid column" or "slug" method of lowering TA. Most pool stores STILL tell people to just dump acid in a particular way to lower TA instead of the correct (far more efficient) technique of lowering overall pH of the pool combined with aeration.

I don't think there is anything you can do to reduce the amount of aeration due to the hydrogen gas bubbles from the SWG other than not run the SWG as often so that means figuring out ways to reduce chlorine demand so that you don't have to generate as much chlorine (i.e. can not have the SWG run as long -- reduce it's percentage on-time). If you have your pool covered most of the time, then it is possible that this will reduce gaseous exchange with the air and reduce the rate of pH rise. I know that in non-SWG pools this works well, but the effect with SWG pools isn't as large as I had hoped as some SWG pool users with pool covers still experience a fairly strong tendency for the pH to rise, though it may be reduced somewhat.

As for pointing the eyeballs down somewhat, it's a catch-22 since you want good circulation of chlorine everywhere so that there's no place where algae can take hold, but you are correct that if you circulate near the surface then you send more chlorine into the area where it can get broken down faster (since there's less CYA above it to shield the UV rays). However, though that's the theory, no one has done an experiment to see if it's true -- that is, if the rate of FC loss is higher with the eyeballs pointed slightly up compared to down. Of course, if the eyeballs are pointed up enough to agitate the surface water, then other things come into play such as increased outgassing of chlorine (mostly hypochlorous acid; to a lesser extent chlorine gas) itself as well as carbon dioxide (in fact, pointing eyeballs up is one way to aerate the water more for the TA lowering procedure). My guess is that the CYA UV protection effect is the dominant factor so circulating near the surface would result in a greater FC loss as you have indicated. Of course, a pool cover that is opaque to UV would cut down such losses the most and that's what I've got in my non-SWG pool resulting in 1 ppm FC per day chlorine usage if used every day and 0.5 ppm FC per day usage when not in use (and that's at a water temperature of 88F) that's probably 1/4 to 1/2 the loss I would would have if I didn't have a pool cover (my pool is usually near 3.5 ppm FC at 30 ppm CYA).

As you point out, the hydrogen gas bubbles are most visible coming out of the returns at night with an interior pool light turned on. I don't know of any potential problems with such bubbles other than the annoying aeration and pH rise effect. Hydrogen gas is a weak reducing agent (against oxidiers) so there are all kinds of theoretical things that could go on including using up some chlorine itself, but I think that effect is probably small (perhaps rate-limited). I've never heard of any flammable effects from SWG pools with pool covers where the trapping of hydrogen gas might be of concern but it probably dissipates through most covers (it's a really small molecule).

A couple of additional points. There does seem to be a decent increase in UV protection from 60 to 70-80 ppm CYA so if you notice a positive trend in reduced chlorine loss, you could bump up the CYA a little more. Just remember to have the FC level be at 4.5% (around 5%) of the CYA level so you prevent algae from growing. The other common thing that is done to reduce chlorine demand and to provide an additional pH buffer that lets you have a lower TA level is to use 30-50 ppm Borates. You do this by adding 20 Mule Team Borax and acid (alternating -- not ever mixed together in concentrated form). The resulting Boric Acid in the pool is an algaecide so inhibits nascent algae growth and can reduce chlorine demand. Whether this helps with your specific pool is a function of other factors such as the pool's phosphate level because if that's really low already then the algae won't grow anyway (so yes, using a phosphate remover is another approach, but more expensive; use of a weekly PolyQuat 60 algaecide is yet another approach, but again more expensive long-term than a one-time addition of Borates).

It takes around 70 cups (7-3/4 boxes; 36.8 pounds) of 20 Mule Team Borax plus 35 cups (about 2.2 gallons) of Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons to raise the Borates to 50 ppm. Lamotte makes the best test strips for Borates (and yes, test strips are the best way to measure Borates and salt; for salt, the Aquachek White test strips are best; for everything else, drop-based tests are better). An easier, but more expensive, alternative for adding Borates is to use Proteam Supreme Plus (about 28 pounds per 10,000 gallons) which is pH balanced to be near-neutral (they use a combination of sodium tetraborate pentahydrate which is similar to Borax though contains less hydrated water and Boric Acid). A link is here.

You will reduce the rate of outgassing and related pH rise by lowering your TA to around 80 ppm and having a target pH of around 7.7. Even doing all of these things will still have some pH rise, but will take far less acid to compensate and will only need to be added less frequently. If you have other water aeration features, such as waterfalls, fountains, etc., then having those turned off as much as possible will also help.

Richard

Share this post


Link to post
Share on other sites

You have been patient, sorry if I implied otherwise.

Had my water tested during lunch today:

CYA 58

TC 8.5

FC 6.3

pH 7.3

TA 102

going to add a a couple lbs of CYA and bump my pH a bit. The rest looks pretty good, I think... FC is a bit higher than I'd like but IntelliChlor output had been set to 60% last night, also it's been overcast the past few days... lowered output to 40% last night, hopefully I'll see my FC drop a bit, then hold between 4-5...

next task: making boric acid...

Share this post


Link to post
Share on other sites

Your Combined Chlorine (CC) = TC - FC = 8.5 - 6.3 = 2.2 seems high, but I'll bet this is a test error since it looks like these are pool store numbers (having measurable CC in a clear pool with sufficient FC and exposed to sunlight is rare, especially in an SWG pool). I'm sure you've seen me write this before, but you should really get your own quality test kit such as the Taylor K-2006 you can get at a good online price here or the TF100 kit at tftestkits.com here with the latter having 36% more volume of reagents so is comparably priced "per test".

By the way, they didn't measure Calcium Hardness (CH). What kind of pool surface do you have -- vinyl, plaster/gunite, fiberglass? Also, forget the advice about an FC level of 1-3 ppm being sufficient. You should have a minimum FC of 4.5% of the CYA level. At your current roughly 60 ppm CYA, that's a minimum of 2.7 ppm FC -- if you raise the CYA to 80, then the minimum will be 3.6 ppm. You can have lower FC levels if you want to, but would then need to use a supplemental algaecide (PolyQuat 60 or a phosphate remover) at additional cost to ensure your pool doesn't get algae.

Except for that, your numbers look good. If you find that the pH has a tendency to rise, then the TA can get lowered a bit to 80, but it's best to do one thing at a time and see how things work out.

Richard

Share this post


Link to post
Share on other sites

Yes, they are pool store numbers - will be ordering a Taylor K-2006 soon. For what it's worth, we've had overcast skies for the better part of the past several days - I guess I'll see if my CC drops after a few sunny days. Any recommendations - besides waiting for the sun? I'm striving to achieve and maintain 3-4ppm FC...

They did measure my CH - it was low (115) but I added 5lbs of calcium chloride this evening and will have a sample tested again this weekend. Was also going to add 2 lbs of CYA tomorrow...

Pool is sparkling, I'm skimming & rinsing skimmer sock 2x/day and vacuuming as needed (every 3-4 days). Pump is on a 10-hour schedule, from 10AM-8PM - is this sufficient, and does it matter whether I run during day or night?

Share this post


Link to post
Share on other sites

Wait to see what your own test kit says about the CC. I wouldn't worry about it now.

If your pool is vinyl, don't worry about the CH. Otherwise, you do need to raise it especially if you run at a lower TA level and higher CYA level (i.e. 80 and 80). A CH of around 300 ppm would work assuming your target pH is around 7.7. If you find you don't have as much of a pH rise problem and target a pH of 7.5 instead, then a higher TA or CH level is needed. Use The Pool Calculator to calculate the saturation index and don't forget to include the salt level in your calculation. A saturation index target of around -0.2 is reasonable for an SWG pool since you want to avoid scaling in the SWG cell so being slightly under-saturated is OK. This doesn't have to be perfect.

As for when to run the pump, what you have is fine but ideally you'll want the SWG to run during the day and your circulation pump to have most of the run time during the day but some at night as well (i.e. split into two on-times), but you may not be able to program your system to have circulation without the SWG being on at night so if you just have the pump running during the day then this is OK (if the SWG is on at night, then the chlorine will likely build up higher at night). In my own pool, the pump runs only during the day, but that's because I have a solar system so it has to be on then and gets more than one turnover as a result. A 10-hour schedule might be longer than you need. Do you know your turnover rate or the Gallon-Per-Minute (GPM) rate on your pump and your pool's water volume? Usually one turnover per day is sufficient, but this depends on many factors including how well water circulates in your pool (i.e. if there are dead spots).

Richard

Share this post


Link to post
Share on other sites

Will low CH potentially damage my equipment? I've added more CaCl and expect my level to be in the area of 275-325. Will confirm w/ next test.

I don't know numbers offhand, but all of my equipment - heater (rarely used), pump, filter (and IntelliChlor unit, for that matter) are all oversized for my pool, and I recall that my turnover rate is high, approx 8-10 hours.

Pool temp is 66F, hoping it reaches 75F+ over the next week so we can finally get in!

I deeply appreciate all of your advice - and will have more questions coming!

Share this post


Link to post
Share on other sites

The CH, along with TA and pH, saturate the water with calcium carbonate. It's purpose is primarily to prevent pitting and erosion of pool plaster (and grout). It doesn't help protect corrosion of equipment very much (it's a debated topic as shown here but the idea that saturation of calcium carbonate forms a protective layer for metal isn't widely held anymore); low pH (mostly below 7.0) in the presence of an oxidizer such as dissolved oxygen or chlorine is what corrodes metal, pump seals, etc. High oxidizer levels are also more corrosive, but in a pool with CYA in it the effective oxidizer level is relatively low (though much higher than in water without chlorine). If the water is over-saturated with calcium carbonate, then it has the potential to cloud or form scale, though the water has to be fairly over-saturated before this occurs in a non-SWG pool. In an SWG pool, the pH at the plate that is generating hydrogen gas gets fairly high so scale can form. This is partially mitigated by a reversal of the polarity of the plates that is done every so often by the SWG system and that causes any scale to dissolve and flake off as the area around the chlorine generating plate is acidic.

It sounds like you've got a plaster/gunite pool, not vinyl or fiberglass. So the Calcium Chloride bringing your CH in line is good.

Share this post


Link to post
Share on other sites

Actually, it's a vinyl pool, so I may have screwed up. I haven't had CH tested since I added some more CaCl two nights ago, but I'm guessing it's now in the 250-300 range.

Share this post


Link to post
Share on other sites

You didn't screw up -- you just added calcium that you didn't need to add (or at least not that much). Don't worry about it.

Share this post


Link to post
Share on other sites

Took a dip after putting the kids to bed. A bit chilly (70F) but opened the pool a month ago and couldn't wait any longer. Should warm up quickly - located in the half walk-out, w/ masonry walls on two sides and a SSW exposure. Richard, thanks so much for your time and advice - I've put it to good use! Ordering the Taylor kit tomorrow...

- Joe

Share this post


Link to post
Share on other sites
Actually, it's a vinyl pool, so I may have screwed up. I haven't had CH tested since I added some more CaCl two nights ago, but I'm guessing it's now in the 250-300 range.

Richard,

Had a sample tested today - still using pool store numbers, but most everything looks good; CYA is 74 and CH isn't as high as I feared - 184. But CC is still high - 1.9 (TC is 6.5, FC is 4.6).

Question: could pollen be responsible for the high CC? I found a prior post where you suggested high pollen could be responsible for high chlorine demand - could it also bind up this much chlorine? Pollen counts have been very high in the St. Louis area this spring - thanks in part to near-record spring rains after last summer's prolonged drought/heat wave. Also, the Cottonwoods in the wooded ravine near our home are producing plenty of seeds.

I can't think of an ammonia source (CYA was low when I opened a month ago).

Don't want to add any more stabilzer, so in lieu of lithium I was thinking of adding 7 gallons of 10% bleach (Vertex) - pool is 16,500 gallons.

Will this free my combined chlorine? Should I even worry about this?

Thanks again, and enjoy the holiday weekend. (Pool is slowly warming, but I'll be using the heater so we can swim this weekend).

- Joe

Share this post


Link to post
Share on other sites

Joe,

I wouldn't worry about your CC until you get your own test kit and verify that it is real. Pollen can create a demand for chlorine and could form some CC so that is a possibility. The best way of removing the pollen is via a skimmer sock.

Richard

Share this post


Link to post
Share on other sites

I've been using skimmer socks since day 1 - leave it in (w/ skimmer basket) during vacuuming too, save for opening and to vacuum shredded leaves to waste after a heavy windstorm a couple weeks ago. My pump pressure has barely budged, so I haven't bothered to backwash in a few weeks. For the past several days I've found mainly bugs in the sock, but for a couple weeks it was heavy with pollen - tan in color and the consistency of dissolved cellulose. At $1 each, socks are a great investment, went through maybe 3 during the spring but based on my experience from the month I had the new pool open last September I'm guessing I can make it through the rest of the season w/ just 2-3 more socks (main problem is snags caused by beatles and lost elasticity after repeatedly removing, rinsing and re-stretching the sock.

I'm going to ignore the CC for awhile, see how my water looks after some hot days and moderate bather loads. I know I can always superchlorinate w/ bleach...

Again, thanks for your ready advice. Pool will be used in full force this weekend...

Share this post


Link to post
Share on other sites

Lower CYA levels work with lower FC levels, but higher total chlorine usage. The SWG works harder to maintain the level, even though you are aiming for a lower level, because more chlorine is lost to sunlight. If your CYA is at 30 or 40, testking 70-536 you can aim for an FC level of 2 to 3.

The point of having ORP is that you don't need to test the FC level very often, nor do you need to adjust the SWG percentage as the seasons change. The ORP controller takes care of adjusting chlorine production to respond to increased bather load, testking 70-298 or reduce sunlight levels, or any other factors that come into play.

I have never found ORP automation to be very useful in outdoor pools. It can make a huge difference in an indoor pool, testking 1z0-050 where chlorine usage varies dramatically depending on bather load. But in an outdoor pool, chlorine usage is fairly steady anyway, because most of it gets used by sunlight, which is fairly regular.

PH automation is far far more useful in an outdoor pool.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...