Ozone is a nice option to have

[Brian@UltraPure]

Split off of this topic. JasonLion

Ignoring the fact that I don't think you should have an ozone system at all, . . .

We do not claim that our Ozone system is a stand alone oxidation/sanitation system, it simply reduces the amount of Chlorine needed to maintain a safe sanitary residual in the pool as well as reducing or eliminating the bulk of "specialty" chemicals. There is no Ozone system in North America that can be used as a stand alone system in a residential application due to safety regulations. To effectively have a stand alone Ozone system you would need to run the pump 24/7 as there is no residual with Ozone, and that will still only take care of the oxidation workload, not the sanitation. Ozone, in a residential application cannot be relied on for sanitation due to the off-gassing of such high concentrations of Ozone gas required. We do not and have never claimed our systems to act as a sanitizer, they are simply there to act as the primary oxidizer, allowing the chlorine to do what it is supposed to do, sanitize. Telling somebody that they don't "need" Ozone on their pool is like saying that you don't "need" air conditioning in your car, but it is a nice option to have.

 

[JasonLion]

In an outdoor residential pool ozone doesn't really help much at all, to the point where it is fairly common for people to post here that they have just realized that their ozone system had not been working for months, yet they never noticed any difference in the pool at all. It makes little sense to spend money installing and maintaing a device which has no perceptible effect.

Ozone typical serves as a secondary oxidizer, with chlorine as the primary oxidizer and sanitizer. In principal, the ozone can oxidize things, so that the chlorine doesn't have to, saving on chlorine. However, in practice, there is so little need for oxidization in a residential pool that the maximum amount of chlorine you can save is very small. The situation is very different in a commercial pool, where the bather load is much higher and there is way more stuff needing oxidation.

In a residential pool, the amount of chlorine required is primarily determined by the amount of chlorine lost to sunlight and the minimum level required to prevent algae. Ozone has no effect on either of these factors, reducing only the amount of chlorine lost to oxidization, which is minimal. Again, in a commercial pool the situation is entirely different. The amount of chlorine required is primarily determined by the oxidation load, and ozone can help with that very effectively.

 

[chem geek]

To add to what Jason has written, the chlorine demand from bather load in a residential pool is extremely low. One person-hour of swimming in 10,000 gallons creates a chlorine demand of around 0.1 and certainly less than 0.2 ppm Free Chlorine (FC). This is far, far less than typically lost in sunlight in one day which is more like 2-3 ppm FC so the chlorine demand with low to even moderate bather loads isn't really seen and the cost savings is minimal. In fact, ozone oxidizes some chlorine to chlorate so can increase chlorine demand rather than decrease it in these situations.

This effect is most readily seen in hot tubs / spas where the bather load is much higher due to the far lower water volumes (typically around 350 gallons). In that environment, one person-hour of soaking in a hot (104ºF) tub generates roughly 7 ppm FC chlorine demand in 350 gallons. When people use the spa every day, then an ozonator typically cuts the chlorine demand in half since the ozone does effectively oxidize much of the bather waste in this situation. However, if the spa is less frequently used, such as once or twice a week, then the ozonator increases the chlorine demand causing a drop of 50% of FC per day instead of the more usual 25% per day with no ozonator. This has been shown over and over again in spas mostly reported at poolspaforum.

The above situations assume there is no urination in the water as that significantly increases chlorine demand. One cup of urine in 10,000 gallons would have a chlorine demand of around 0.6 ppm (see this post for source details). So a pool full of urinating children (or adults, for that matter!) could benefit from supplemental oxidation such as that from an ozonator, though simply adding more chlorine would also do the trick and one would hope that this situation isn't that frequent.

So while ozonators clearly have a reasonable place in pools and spas with high bather loads, such as most commercial/public pools and spas and in frequently used residential spas, they really aren't very valuable for outdoor residential pools or less frequently used residential spas. Indoor pools, including indoor residential pools, can have other issues in terms of Combined Chlorine (CC), so supplemental oxidation to deal with CC can be useful -- either an ozonator or a UV system since there is no sunlight to help breakdown more persistent CC more quickly.

Richard

 

[chem geek]

We do not claim that our Ozone system is a stand alone oxidation/sanitation system, it simply reduces the amount of Chlorine needed to maintain a safe sanitary residual in the pool as well as reducing or eliminating the bulk of "specialty" chemicals.

Also, with regard to eliminating "specialty" chemicals, the tens of thousands of members and lurkers here at TFP and also at The PoolForum and other websites almost all maintain their pools using no algaecides, phosphate removers, clarifiers, flocculants or even weekly shocking. Typically, they use bleach or chlorinating liquid and some acid. That's it, period.

For example, my own 16,000 gallon pool shown here and here has an electric opaque pool cover so has a fairly low chlorine demand of 1 ppm FC per day from it being used 1-2 hours every day and longer on weekends. I add 12.5% chlorinating liquid twice a week plus a small amount of acid every month or two and this costs me around $15 per month. That's it. Even those with higher 2-3 ppm FC per day chlorine demand would spend less than $50 per month on chemicals for this size of pool though would need to add chlorine more frequently.

An ozonator is not going to help reduce chlorine demand by an amount that is noticeable. Yes, you can certainly find people spending far more shocking their pools with chlorine or using more chlorine fighting nascent algae blooms usually due to high CYA levels where putting in an ozonator seems to magically help, but such pools could easily be managed by killing off the algae by shocking (and possibly lowering the CYA level) and then simply maintaining an appropriate Free Chlorine (FC) level relative to the Cyanuric Acid (CYA) level as described in the Chlorine / CYA Chart.

As for reducing the level of chlorine needed to be sanitary, it takes a very low level of chlorine to kill most pathogens so that really isn't the issue. It takes much higher levels of chlorine to prevent algae growth and that is what really determines the chlorine level needed in a pool, especially one with CYA in the water since it reduces the active chlorine (hypochlorous acid) level to close to the algae inhibition level. This is why one must make sure that their FC level is sufficient relative to the CYA level -- not doing so in a pool rich in algae nutrients will lead to rapid algae growth. Chlorine alone can prevent algae from growing, but the level of active chlorine must kill algae faster than it can reproduce. If one really wanted to be able to significantly lower the chlorine level, then one could use a supplemental algaecide (in the bulk pool water) such as PolyQuat 60 at extra cost, but this is of course not necessary.

Telling somebody that they don't "need" Ozone on their pool is like saying that you don't "need" air conditioning in your car, but it is a nice option to have.

In an outdoor (low bather load) residential pool, it's not like an air conditioner, but more like gold-plating the engine -- something you can't see, but you pay a lot for, and can't really tell much of a difference.

If someone were seriously concerned about Cryptosporidium and let people with diarrhea in their pools, then an ozone or UV system can give them some additional protection assuming the water circulates for multiple turnovers (i.e. many hours) after an incident before someone else is exposed to the oocysts. Again, such systems make more sense in commercial/public pools where one person can infect hundreds, but is not practical for a residential pool.

 

[Richard320]

Someone 'splain this to me.

Ozone will oxidize things? To me, that sounds like it would be really useful in an indoor pool, or one that gets so much use it always looks cloudy. I can think of a couple hotel pools I've seen recently that could benefit from an ozonator.

 

[chem geek]

Ozone will oxidize things?

Yes it will. So yes, it is useful in any situation where a supplemental oxidizer would be helpful such as pools with higher bather loads and frequently used spas and sometimes in indoor pools though UV is more common in this latter situation. In high bather load pools, the main options for supplemental oxidation are ozone, UV, non-chlorine shock (MPS) and enzymes. Technically, UV isn't oxidation, but it does break apart many important molecules nevertheless and like sunlight it produces some free radicals from some breakdown of chlorine. A saltwater chlorine generator system can also be considered as partially improving oxidation since a portion of the water through the cell gets very high chlorine levels at low pH but it's not always enough by itself for high bather load pools.

Ozone is a stronger oxidizer than chlorine so will even oxidize chlorine itself to chlorate.

As to whether the cloudy hotel pool really needs an ozonator or whether the problem is simply too low an FC/CYA ratio such that oxidation from chlorine is too slow or algae is starting to develop, that's hard to say. If the bather load is truly high, then an ozonator can be very helpful, though the other oxidation sources would work as well (i.e. MPS and enzymes and to a lesser extent UV and SWG).

Another benefit of using supplemental oxidation, such as ozone, in high bather load pools and spas is that it reduces the amount of disinfection by-products (DBPs). These form proportionally to bather load so aren't an issue in residential pools, but high bather load pools can generate far more DBPs. Indoor pools can be a particular problem because they typically don't use CYA so that may end up generating orders-of-magnitude more irritating and volatile nitrogen trichloride. Though using a small amount of CYA should help, having supplemental oxidation is also very useful to oxidize organics (such as urea) before chlorine gets a chance to do so which then creates DBPs.

 

[Chasville]

I have been using an Eclipse Ozonator on my pool for 3 years now.

IT DOES HELP!!! and anyone who tells me it doesn't or can't doesn't really know.
BUT, IT IS VERY COSTLY "help"

I have a very high demand outdoor pool because it gets a lot of debris in it regularly, which I have explained before.

Here's the scoop.
Ozone is the strongest oxidizer available, but it bubbles out of the water or decays into straight oxygen very quickly. In seconds, or at most a few minutes. So, there is not really any practical residual ozone level in the water to deal with the pool walls, floors, etc. You have to have something else in the water, such as chlorine or bromine or ionized minerals.

I have also been experimenting with using mineral ions = copper, silver, zinc.
Ozone is not compatible with the use of the mineral ions because it oxidizes them, literally, into copper oxide, silver oxide and zinc oxide, effectively removing the ions and their benefit from the water. Mineral ionization is a workable solution for some circumstances, but not all, and it is also shrouded in controversial market hype from the ionizer community -- pro -- and from the chemical community -- con. I won't comment about it more here, as it would be a distraction.

How does the Ozone help?
It helps in my case because the pipes from the introduction of the ozone to the pool inlets are greater than 10 feet long. The ozone is mixed with all the water that is returning to the pool. It is held captive in the piping giving it more time to work with what's in the water before it gases/bubbles out. Since the ozone is a stronger oxidizer than chlorine or bromine, it converts the "...amines" releasing the chlorine and bromine back into their "...ide" useful state. The ozone acts like a shock.

Before I added the ozonator, I needed 4 to 6 gallons of bleach a week to maintain the pool. After the ozonator, I needed 2 to 3 gallons a week, and I didn't have any CC levels. The ionizer further reduced my need, but that, again, would be a distraction from this thread.

This is real world experience by an actual user of the product(s).

As far as the suntan oil, body oil, etc. goes. Unless the ozone is introduced at the skimmer inlet and pulled through the piping before it gets to the filter, the ozone will do nothing with this stuff. I have a DE filter, and the oils glom (glaum? -- what's the correct spelling?) gunk up there.

If any viruses or bacteria are in the water after the filter, then what the ozone contacts, is destroyed there, in the pipes, before the water returns to the pool. Only, the chlorine should have already done that before it got to the filter in the first place.

Now, as to the economics of the situation?
The ozonator cost > $1000, which would buy > 900 gallons of bleach from Aldi's, which at 6 per week and a 20 week season is more than a 7 year supply; and at saving 2 to 3 gallons per week would take more than 14 years to "pay for itself".
Again, this is for my pool, which has high demand due to debris, not bather load.
So, for a low to medium demand pool, the payback time is even longer.
All the ozonator would save is "shocking" to reduce CC levels, or to convert broma... back to bromide.

I am now in the process of trying to decide, do I drop the ozonator and keep using the ionizer, or do I keep the ozonator and drop use of the ionizer, but that is for a different thread.

 

[teapot]

Chasville, an interesting post, thank you. I look forward to your next subject post.

 

[JasonLion]

Since the ozone is a stronger oxidizer than chlorine or bromine, it converts the "...amines" releasing the chlorine and bromine back into their "...ide" useful state. The ozone acts like a shock.

This is not true in a chlorine pool, though it is true in a bromine pool. When ozone reacts with chlorine, or chloramines, both are broken down and deactivated. Bromine is different. Bromine is reactivated by ozone. However, using ozone in a bromine pool will also produce bromates, which are a suspected carcinogen.

Before I added the ozonator, I needed 4 to 6 gallons of bleach a week to maintain the pool. After the ozonator, I needed 2 to 3 gallons a week, and I didn't have any CC levels.

To see that much effect, you probably have bromine in the water. Ozone reactivates bromine, so you don't need as much chlorine to reactivate the bromine. You wouldn't see numbers like that in a chlorine pool with a low bather load unless there was something else going wrong pre-ozone.

 

[chem geek]

I have a very high demand outdoor pool because it gets a lot of debris in it regularly, which I have explained before.

Before I added the ozonator, I needed 4 to 6 gallons of bleach a week to maintain the pool. After the ozonator, I needed 2 to 3 gallons a week, and I didn't have any CC levels. The ionizer further reduced my need, but that, again, would be a distraction from this thread.

All the ozonator would save is "shocking" to reduce CC levels, or to convert broma... back to bromide.

You bring up a good point about pools that get a lot of debris since that can be similar to a high bather load, especially if that debris has a higher chlorine demand such as pollen and other debris that is organic and has a lot of surface area (leaves and other large objects usually aren't as much of a load). If chlorine demand is higher due to the debris, then an ozonator will help if that debris is fine enough to not get caught in the filter (though chlorine demand remains high until you remove such debris from the filter).

4-6 gallons per week in 21,000 gallons is 12-18 ppm FC per week or 1.7-2.6 FC per day which is not that high if the pool is exposed to direct sunlight. In this post you said you added chlorine twice a week so would have been adding at least 6 ppm FC at a time which is a fairly large FC swing so the FC may have been low when you added more chlorine or your target range was higher than it needed to be -- it is more usual to add chlorine more frequently for a more consistent level; otherwise invisible nascent algae growth can occur when the active chlorine level gets low and that increases chlorine demand. In this post you reported something that may have been algae though might have been some form of staining (from earlier Floatron copper ions?).

So to me it sounds like you are mostly using the ozonator and now an ionizer as supplemental methods to control algae and that lets you use a lower active chlorine level. The absolute loss from sunlight would then be lower in that case since it is proportional to the active chlorine level. This is similar to what I wrote above when I said that you could use a supplemental algaecide (at extra cost) to allow for a lower chlorine level. With an ozonator alone, this approach won't always work because it doesn't kill algae on surfaces -- only free-floating algae during circulation through the ozonator -- but with a copper ion system algae growth can be inhibited but with the risk of staining plaster surfaces.

When you started using your ozonator, did you find that the FC didn't drop as low or was it that you could just have a lower FC/CYA ratio and not get algae? If the former, then the ozonator reduced chlorine demand probably from oxidizing some debris; if the latter, then you were using the ozonator as a supplemental algaecide though as you've pointed out before that doesn't help protect against algae attached to pool surfaces. Is your pool exposed to direct sunlight or do you have a mostly opaque pool cover? Your current daily FC usage of 0.8 ppm per day could not occur in a pool exposed to direct sunlight in spite of an ozonator unless the FC was low and the CYA was high since the ozonator does nothing to protect chlorine breakdown from sunlight. Did you ever use a sodium bromide product such as "No Mor Problems"?. As Jason noted, if you've got bromide in your pool, then ozone will oxidize that to bromine so would be like a bromine generator and reduce chlorine demand. Note that I've been assuming that the bleach you have been using is 6% and that you really mean "gallon" and not jug of chlorine that is normally 3/4-gallon (96 fluid ounces) or 1-1/2 gallon (192 fluid ounces).

Richard

 

[chem geek]

I would like Chasville to answer my questions in bold from the previous post since that would be helpful in understanding, but in the meantime I've looked at other ozonator posts to see if there are trends. While there are many posts as I described earlier in another forum on spas that very much conclude that ozone cuts chlorine demand a lot (roughly in half) when there is bather load while it increases chlorine demand a lot (almost double) when there isn't bather load (at least in spas), the number of posts/threads regarding ozonators in pools on this forum is comparatively low. Nevertheless, here's some of what I've found.

First, this post from Chasville early on indicates only one gallon per week of chlorine usage after using an ozonator and Floatron which is extraordinarily low at 0.4 ppm FC per day. Unless the pool doesn't get direct sunlight or is covered by a mostly opaque cover, then it does seem likely that there is bromide and therefore bromine in the pool instead of chlorine since an ozonator will act like a bromine generator when bromide is present so the apparent chlorine demand would indeed be lower (and the chlorine tests do not distinguish between chlorine and bromine). The only downside to this is the production of some bromate which is a suspected human carcinogen (in general, brominated organics are more carcinogenic than chlorinated ones, at least for those typically found in pools & spas).

Some people reported problems with their ozonator systems such as algae (also high chlorine demand, but that's more likely due to the algae), another user with an ozonator and algae, yet another user with an ozonator and algae, oxidation of CYA (haven't seen this before, however), another member reporting algae and another with low FC.

There was another member who saw reduced chlorine demand with their ozonator.

One member tried doing a test to see if ozone got rid of chlorine. The experiment had a drop in FC and a rise in CC consistent with ozone being in the water as most oxidizers (including MPS) will register as CC while mostly chlorine and bromine register in the FC test. Another member with field experience wrote an excellent summary here including their observation that most people who have ozonators that then fail don't even notice the difference.

So while there are no doubt situations where either a high bather load or high organic demand result in an ozonator lowering the chlorine demand such as in commercial/public pools, regularly used spas (both commercial/public and residential) and perhaps some residential pools, and while using an ozonator in a bromine pool would also lower sanitizer demand, it may be that for many chlorinated residential pools the ozonator gives a false sense of security such that the FC level is lowered too much relative to the CYA level with the result of algae being able to grow.

Richard

 

[Pontiac]

To add a little something, I have talked to some close friends of mine who also own pool services. Combined, we are servicing over 1000 residential pools. And all of us agree, that we see nothing different going on in pools when ozonators are disconnected.

 

[Chasville]

First, I'm surprised no one picked up on the cost of the ozonator, and the payback time. Curious.

Chem Geek.

The pool may have had some bromine in it. No way for me to tell.
My first year I did a terrible job of testing, using only an AquaChem kit that tested chlorine and pH. I also was using testing strips, which you all know are not reliable. Last year, when reporting here I did a better job. This year, I've not done much testing, which is just plain lazy and unscientific.

I buy chlorine bleach from Aldi's. I think they're gallon jugs, but they could be 96 oz. I'll check next time I'm there, don't have any in reserve right now.

The pool is open to the air 24 hours a day from opening to closing. We put the pool cover on in late September to keep out the "Fall", and to hold in some ground heat in the winter, since we don't drain the pool, and I don't keep the pump running. Most NC people keep the pump running during winter to prevent freezing. I drain the pump and filter and lower the water level, but Fall and Winter rains just fill it back up.

So, in answer to the direct sunlight question, yes it does get a few hours of direct Sun light. The Trees shade it for another few hours in the morning and evening. The tall pines are starting to shade the south end as the Sun is lowering -- approaching the Autumnal Equinox.

My practices have been rather sporadic, other than running the AquaBot every two or three days to keep the pool swept -- debris build up, including sand and dirt from rain wash.

Right now, I have turned off the Ozonator, and fully opened the by-pass valve so essentially no water is sucking air through the venturi port. I am going to see if the floatron will be able to successfully build the copper level up to .3 ppm. I want to maintain this setup until close this year.

I believe there had been some plating of the copper onto the stainless steel latter, but perhaps not because I was able to wipe it off. There may be some staining at the joints of the fiberglass panels, but I have not good way of knowing. I may find out when I close and drop the pool level way down this year so that I can recaulk all the joints -- fiberglass to cement, fiberglass to fiberglass. It is my understanding that staining really doesn't become an issue until the copper has a much higher concentration. When I have dropped the water level, I will try using some CLR and "clean" what may be copper stains.

The last two years, I replaced a lot of the water in the pool, so sodium, calcium, CYA, and ?bromine? levels would have fallen a lot.

If the OTO chlorine test tests for bromine, then I can be sure I have none, since it does register the chlorine when i add it, but I have let it fall to zero on many occasions. I know, this is not advisable.

The current experiment is this:
I super chlorinated with 8 bottles of bleach to be sure I've killed all resident algae in the pool, and in the joints where it is hard to brush.
I am running without the ozonator, and working on building up copper ion levels.
I put in 1 trichloro-s-... tablet to provide some CYA and maintain a very small residual chlorine until the copper level builds up.
We have had a slight metallic aftertaste in the water, and a dusty smell. I'm thinking it is the metal oxides doing this.
I want to see if the algae stays under control.
I want to see if the water looses its "sweetness"
I want to see if the aftertaste changes -- you can't help but get some water in your mouth after all.
I have some calcium hypochlorite (chloride?) that I will use if I need to add some chlorine in the evenings.
I did measure the pH recently after a few days with the tablet in, and used the POOL Calculator to determine how much baking soda to add to raise the pH back up -- it had fallen to 6.8. It is currently running about 7.4 to 7.6, depending on color interpretation and the pH test used (AquaChem vs. Red Sea aquarium test kits).

Is this enough?

So, as mentioned many times before. Ozone can help, but it depends on when it is added, where it is added, and how long it can be in contact with the water. Even so, it is definitely not a cost effective measure when compared to other systems. It also is not a standalone system for swimming pools. It is a very effective sanitizer for drinking water, which is why is it used in the bottled water industry, but that is a whole different circumstance.

The most cost effective system, to date, is BBB with CYA and maybe some muratic (sp?) acid.
But, the boron in the borax is also a toxic element that can sterilize soil, and cause aquatic issues down stream.
Plus it is toxic to insect life -- good to help keep mosquito populations down, bad for bees that drink from the pool, bad for dragon flies that eat mosquitos.
The borax works to help stablize the pH against the sodium bicarb pull. I don't think there is anything else that would work as well.

Copper + Silver + Zinc ionizers work best in indoor pools. These are also controlled toxins to downstream aquatic life. So, if you want to use it, you should dump the water into the lawn/landscaping, not down a storm sewer.

Many grasses can handle higher sodium "salt" levels. But a lot of flowers -- roses -- don't so well. Draining a BBB pool into your landscaping could spell disaster over time. Boron is supposed to be an essential nutrient to help sugar metablism in the plants, but enough kills many plants. In fact, I have found that borax + the right RoundUp will kill Yucca plants, which are otherwise impossible to be rid of.

So, if you use Bleach and Baking Soda + some CYA, you can dump the water down the storm sewer without too much issues, and keep your pool in great shape. SWG also work well.

As far as Ozone is concerned. You get it because you don't mind spending the extra money for the extra oxygenation in the water and some additional anti-microbial action at the mix point, however implemented. It is NOT a sound economic decision. it is not very compatible with mineral ions, and only helps to reduce some chlorine or bromine requirement.

All sanitization methods ultimately require some amount of chlorine, even if only once per week. That is what I have found in reading, and in practice.

 

[Chasville]

Missed a question.

I have generally used algae control as the measure of my success, until this year.

With the DE filter, all the stuff running, and the high water temps, this is the first time we may have run into a bacterial issue for a few days.
Adding some of the calcium hypochlorite clarified the water.
It was getting a little slimy and a slight smell had developed.

At the opening in May, there was a definite beginning odor that was gone in two days, due to ozone + chlorine shock -- calcium hypo....
The DE filter + shock clarified the pool in only one day, but the odor took a second day to be fully cleared.

I plan on replacing my current AquaChem and RedSea test kits with a Taylor kit or kits, and/or an automatic system (was it ColorQ?) since I don't always trust my eyes, for next season.

 

[teapot]

Copper + Silver + Zinc ionizers work best in indoor pools. These are also controlled toxins to downstream aquatic life. So, if you want to use it, you should dump the water into the lawn/landscaping, not down a storm sewer.

Why do you believe ionisers work best in indoor pools?
BTW the level used in pools is less than the EPA allow in drinking/bottled water so it won't harm very much at all.
The levels of salt used seldom harm anything
One of my customers dumped 10ppm chlorine shock water on a farmers crop. The crop was 2 weeks behind in growth compared with crops that didn't get chlorine shocked however 2 weeks later they had caught up and there was no obvious difference.

 

[chem geek]

The pool may have had some bromine in it. No way for me to tell.
:
If the OTO chlorine test tests for bromine, then I can be sure I have none, since it does register the chlorine when i add it, but I have let it fall to zero on many occasions. I know, this is not advisable.

Bromine shows up in OTO, but bromide does not (similar to chlorine vs. chloride) so there isn't an easy way to tell if you've got bromide in your pool and any bromide will become bromine when an oxidizer is used, such as chlorine or MPS. About the only way to measure bromine distinct from chlorine is to 1) measure the FC level and if very low add some chlorine to raise it and wait a few minutes, 2) add enough ammonia to have all of the chlorine or bromine combine to form monochloramine or monobromamine, 3) within a minute or two, measure FC and CC accurately with a FAS-DPD test kit. If there is only chlorine, then all of the FC will get converted to the same amount of CC (if you want too long, the CC will start to drop). If there is any bromine, then there will still be FC showing up. You can do this kind of test in a bucket of pool water. It takes a very small amount of ammonia so even 1/8th teaspoon in a 2 gallon bucket of pool water would be way more than enough for this experiment. 1/4 teaspoon of 6% bleach in 2 gallons is 10 ppm FC, but the test has to be done on pool water since you want to detect bromide in the water.

But, the boron in the borax is also a toxic element that can sterilize soil, and cause aquatic issues down stream.
Plus it is toxic to insect life -- good to help keep mosquito populations down, bad for bees that drink from the pool, bad for dragon flies that eat mosquitos.
The borax works to help stablize the pH against the sodium bicarb pull. I don't think there is anything else that would work as well.
:
Boron is supposed to be an essential nutrient to help sugar metablism in the plants, but enough kills many plants. In fact, I have found that borax + the right RoundUp will kill Yucca plants, which are otherwise impossible to be rid of.

Concentration means everything. You can read about borates safety in this thread that you've seen before. Boric acid is used in concentrated form for controlling insect populations, but you are correct that honey bees drinking only water with boric acid at 17.5 ppm Borates level (ppm Boron) over a period of time had 50% mortality, but flies in general and mosquitos did not have such effects at the lower levels found in pools -- flies needed 5000 ppm while mosquitos needed 500 ppm over 24 hour exposures for mortality levels. There are varying opinions on whether bees are attracted to chlorinated pools (see this post and this link). Some plants can be affected so backwashing water should have watering done subsequently for dilution (the same can be said for salt pools).

The borates add additional pH buffering, but they don't directly eliminate the carbon dioxide outgassing so in theory you still need to add as much total acid -- you just add a larger quantity less frequently but the total is still the same on average "per month". There are indirect effects that can reduce the rate of pH rise, but this seems mostly related to killing nascent algae growth letting one turn down SWG cell on-time so doesn't work in all pools since there may not be much growth in pools with sufficient chlorine levels.

 

[learthur]

I can add from personal experience that low dose chlorine (<1pm
) plus ozone regardless of how low your CYA is will NOT inhibit algae growth where I live.

Also ozone use is all about contact time. Since most installations don't include a 200-300 gallon contact tank and most pool ozone generators produce small amounts of ozone for a pool, ozone will have a minor benefit regardless of how you view it.

The exception I have found is when I put my plumbing in spa mode. The ozone does a great job when confined to my 600 gallon spa. Especially with high water temps. And since I only activate this setup when people are in the spa, the ozone coincides with bather load.

 

[teapot]

) plus ozone regardless of how low your CYA is will NOT inhibit algae growth where I live.

And I agree, because algae simply do not oblige by free floating into the skimmer and into the ozone chamber. Algae sticks to the walls and floors thus preventing the very short lived ozone from doing anything really worthwhile. Same as U.V.

 

[jdjeff]

I use a Clearwater Tech A8e ozonator and an 80 gallon contact tank. 8 grams an hour of ozone with the oxygen concentrator. I keep a residual amount of chlorine of around .5ppm (or as close as I can reasonably get it) and my chlorine demand is very low. My oxygen concentrator went out and I was without the ozonator for almost 2.5 months. The difference in water quality and clarity was stunning. The pool was otherwise balanced but I was constantly fighting algae and water that never seemed quite as clear. And this is before it got really hot in Houston. The clarity issue I tried to attribute to nostalgia but when I put the ozonator back into service within 2 days my problems had disappeared. The water really does sparkle and it is noticeably softer. I also notice that I need to backwash more frequently with the ozonator running as it is causing more "stuff" to flocculate and get caught in the filter media. This is particularly true when I fill from my well water, which is high in iron. I also noticed in the no-ozonator time that I had to constantly brush dirt of the walls...several times a week at least. It was horrible. With the ozonator on, there is no dirt on the walls. It all clumps up and goes to the filter. Like magic. I was so shocked by that (and wondered if it was just an environmental difference) that I turned the ozonator off for a week...and the dirt came right back.

I do run the system 24 hours a day on a combination of low (day) and high (overnight) speed (the filter pump through an in floor system). The combination of surface and floor circulation (including a leaf trapper pump) appears to really help. I add no chemicals other than a hockey puck every week or so. No clarifiers, no ph or alkalinity balancers, no algaecides. I'm not saying you can't get similar results through a lot of other work, but this set up has been fantastic for me and is much more set and forget (although I still obsessively check my pool chemistry...10 years of public pool managment is too hard to shake). Down side is of course cost. Most of the small systems don't generate enough ozone to make a difference...especially where it is hot an humid. So if you do it you need to size it right and get a system that dries the air and has an oxygen concentrator. Also need to make sure there is enough contact time with the water to get it clean. I noticed that when I put in a pool chiller this summer (one of the evaporative ones...it is excellent!) and brought my water temperature down, the ozone persisted long enough that I could get a whiff of it from time to time. So I actually turned down the production a bit. It clearly seems to be making it into the pool water, but I want it to be gone by the time it reaches the surface. Anyway, just my experience. It is an option, but one I won't do without it.

 

[teapot]

jdjeff, have you any water figures during that time?
If you have cyanuric acid in the pool then 0.5ppm of chlorine may not have been sufficient to sanitise the water, a little more chlorine may have done the trick. Compared to the outlay for the ozone kit it would seem inexpensive to use chlorine at a slightly higher concentration.