Maintaining FC with Ozonator

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henry89056

Will preface by saying, I am just finishing a multi-day shock process to clear pool of algae due to some neglect on my part through the winter. Pool is sparkling clean now with FC loss around 1ppm for past 2 nights when performing the nightly loss test. Thank goodness for TFP. Thought I'd never get it all gone. Also added 50ppm borates to help maintenance.

A couple relevant details before the subject questions. Last year, we opened a 25,000 gallon plaster pool with natural sandstone coping and decorative rock waterfall, 2.5 Jandy VSP, Del Ozone Eclipse 4 Ozonator (50k gal "primary"), Pentair 320 Chlorinator (takes about 8 tabs) which is currently configured to feed water from the bottom. The pool builder recommended the in-line chlorinator and ozonator (wasn't my idea). I attached pictures of the Chlorinator and Ozonator to the post.

In non-BBB operation (e.g. relying on the 320 Chlorinator) I have a hard time keeping enough residual chlorine in the pool. Last summer, a typical measurement was around 1ppm (clearly it vacillates day-to-day, but this is a rough moving average). I thought the added daily ozone would help, but clearly I was mistaken (hence the algae mess I've fought over the past 3-4 days).

I am wondering a few things about my current sanitizing setup:
1) would having such a large ozonator attached to the sanitation system account for my inability to maintain FC (again, relying only on the 320)?
2) should the Pentair 320 Chlorinator be sufficient to maintain residual chlorine (with or without the Ozonator)?
3) is it worth - perhaps - considering selling the Del Ozone unit (less than 1 year old and should have a long life left)?
4) given I sometimes travel for days at a time, would complimenting (or replacing) the Ozonator/Pentair 320 with a SWG make sense for maintenance purposes? Also in light of natural rock and potential corrosive affects?

I realize I'm fishing with a net here and know this post covers a lot of ground in terms of potential responses. I guess I am more looking for opinions on what to do - if anything? Would you tweak, amend, overhaul this setup in favor of something else? And assuming I can't be around 100% of the time and reliably perform BBB method?

Any suggestions would be helpful.

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1) It might, though there isn't enough information here to tell.
2) Yes, if properly installed and turned up to high.
3) I would.
4) If it wasn't for the stone work, absolutely. Given the stonework, it depends on what kind of stone it is and how you feel about sealing the stone.
 
Regarding #1, I'm not sure what else I can say regarding the Ozonator. How do you measure Ozone impact to a sanitation system?

I suppose I could remove the ozone supply tube and check the difference.

Will have to noodle on SWG. Thinking about selling the Ozonator and installing an SWG to make 'away' maintenance easier.

Thanks!
 
My opinion is that an ozonator will only cause you problems and won't give you any benefit*. It causes iron to turn into stains and it destroys chlorine.

*There are some applications that might benefit from ozone, but only under specific conditions and very carefully operated.
 
Ozone vs. NOzone is kind of a regular thing around here, and it is a topic which can escalate way beyond tolerance, so I want to be real careful here.

Ozone can kill things in water. It's used in some commercial water treatment, and can be quite effective, BUT, it works in situations where 100% of all water is guaranteed to pass through the Ozonator and can be kept in a closed system to avoid re-contamination, such as a potable water supply system.

In an pool, however, water is treated and returned to co-mingle with the rest of untreated water and recontaminate. If there is no residual sanitizer, then all of the pathogen-killing effects of the ozone will be negated. Assitionally, bear in mind that there is never any guarantee that all of the water in a pool actually and physically goes through the pump. We may move the full amount of water contained in the pool, but it is not a positive-displacement system, and there is always the possibility that swirls, eddys, and other circulation issues let some water stay in the pool proper and remain untreated. This is why some sanitizer must be maintained in pool water, and for that, the hands-down winner is chlorine.

Additional notes:
1) Ozone will deplete some chlorine.
2) Chlorine will deplete some ozone, too, but since ozone systems have to be designed so that there is no ozone left in the water outside of the cell, that's pretty moot.


The bottom line is that you're gonna need chlorine, and how much is going to depend upon where you set your CYA level. If you maintain the FC level properly, there is nothing for the ozone to do except help deplete FC, and if you don't maintain the FC level properly, you will need more than just the ozone to fix the resultant problems.


Now to your questions...

1) would having such a large ozonator attached to the sanitation system account for my inability to maintain FC (again, relying only on the 320)?
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While ozone will deplete some chlorine, in reality, your inability to maintain FC is due to an organic demand. You are fighting something in the water.

2) should the Pentair 320 Chlorinator be sufficient to maintain residual chlorine (with or without the Ozonator)?
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Perhaps, but not for long. Assuming no algae or other nasties to consume your FC, your tablet dispenser will add chlorine at some level on a continuous basis, but will also be adding CYA at the same time. As the CYA levels rise, the given FC level will become less and less sufficient until it will no longer be effective at all. And it will not take as long as you might think.

3) is it worth - perhaps - considering selling the Del Ozone unit (less than 1 year old and should have a long life left)?
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Ummm... maybe? I personally think that used ozone systems would be kind of a buyer's market, but if your ultimate decision is to remove the unit, then whatever you can get out of it may help.

4) given I sometimes travel for days at a time, would complimenting (or replacing) the Ozonator/Pentair 320 with a SWG make sense for maintenance purposes? Also in light of natural rock and potential corrosive affects?
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An SWG would certainly handle the task, but I cannot speak to how it may or may not affect the stone. And while it's not the best thing for general use, the 320 could get you through your vacant days if you are careful with the puck feeder, using it only for travel times, and are meticulous in monitoring and correcting your CYA levels.
 
As described in Chemistries of Ozone for Municipal Pool and Spa Water Treatment and as originally described in the scientific peer-reviewed paper Kinetics and products of the Reactions of Ozone with Various forms of Chlorine and Bromine in Water, ozone reacts with hypochlorite ion to produce 77% chloride ion and 23% chlorate ion.

Because of this, ozone doesn't make very much sense for use in residential pools because the bather load is low so the ozone ends up mostly just being another source of chlorine demand. Turnover times are too long for ozone to have much of an effect on the small amount of bather waste. Also, for outdoor residential pools, the breakdown of chlorine from the UV in sunlight produces hydroxyl radicals that help to oxidize some bather waste so supplemental oxidation isn't usually needed. Ozone makes much more sense in high bather load situations such as in commercial/public high-use pools and spas as well as in residential spas used every day or two. It might make some sense for indoor residential pools, though usually UV is used in that situation.

In fact, we see this ozone/chlorine vs. ozone/bather waste effect in residential spas where spas with ozonators that are used every day or two use roughly half as much chlorine as spas without ozonators under the same every day or two usage. However, spas used infrequently, only one a week or so, have roughly twice the chlorine demand (daily chlorine loss) with ozonators compared to spas without ozonators. Obviously, the amounts vary depending on the strength of the ozonator, the precise bather load, and the size of spa, but the principle remains the same.
 

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chem geek said:
As described in Chemistries of Ozone for Municipal Pool and Spa Water Treatment and as originally described in the scientific peer-reviewed paper Kinetics and products of the Reactions of Ozone with Various forms of Chlorine and Bromine in Water, ozone reacts with hypochlorite ion to produce 77% chloride ion and 23% chlorate ion.

Because of this, ozone doesn't make very much sense for use in residential pools because the bather load is low so the ozone ends up mostly just being another source of chlorine demand. Turnover times are too long for ozone to have much of an effect on the small amount of bather waste. Also, for outdoor residential pools, the breakdown of chlorine from the UV in sunlight produces hydroxyl radicals that help to oxidize some bather waste so supplemental oxidation isn't usually needed. Ozone makes much more sense in high bather load situations such as in commercial/public high-use pools and spas as well as in residential spas used every day or two. It might make some sense for indoor residential pools, though usually UV is used in that situation.

In fact, we see this ozone/chlorine vs. ozone/bather waste effect in residential spas where spas with ozonators that are used every day or two use roughly half as much chlorine as spas without ozonators under the same every day or two usage. However, spas used infrequently, only one a week or so, have roughly twice the chlorine demand (daily chlorine loss) with ozonators compared to spas without ozonators. Obviously, the amounts vary depending on the strength of the ozonator, the precise bather load, and the size of spa, but the principle remains the same.
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ChemGeek, If you owned a pool that already had ozone installed would you:

1. remove it and try to get a few dollars for it on Craigslist
2. leave it connected and running as set up by the pool builder
3. leave it connected and only turn it on for pool parties and etc. when bather load is high.
4. other?
 
Thanks for all the info. I'm thinking of:

1) Removing the 320 and Eclipse
2) Sealing the stone
3) Installing a SWG

There is always a buyer for #1 on eBay ...
 
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