Conversion of bromine pool to chlorine

[BobbyR]

Bromine is confusing. One thing I don't really understand is why it is necessary to keep adding bromine after a reserve is established. Seems you should be able to simply add chlorine, either liquid or tabs, and that would continually activate the Br reserve, without the very high cost of bromine tabs. I have tried this over the past week or so since posting on the subject of bromine to chlorine conversion and it isn't effective. Br/cl level spikes with addition of bleach or oxidizing shock, then quickly drops off to zero. Continuous Br feed seems to be required. Even then, at max feed setting, Br never rises above 1 ppm. I still don't get why I can't just switch to cl tabs and run a cl pool (without emptying the pool first). Bromine tabs cost fortune and are getting worse.

 

[chem geek]

Re: Need help with bromine pool

I have tried this over the past week or so since posting on the subject of bromine to chlorine conversion and it isn't effective. Br/cl level spikes with addition of bleach or oxidizing shock, then quickly drops off to zero.

Why do you think this implies that the bromide reserve isn't there? Your test kit can't distinguish between chlorine and bromine so why do you assume there's no more bromine being produced? That's not likely to be true, assuming you had a reasonable bromide bank to start with. The bromine only declines relatively slowly over time. It sounds to me that if the level is quickly dropping to zero then you aren't using enough oxidizer to handle whatever is going on in the pool or something is growing in the pool consuming the disinfectant.

This is consistent with your continuous feed not being able to get the bromine level up. You simply are not adding enough, either because you didn't calculate how much you would typically need properly or because you've got unusual demand in your pool. Just as with chlorine, you can do an overnight bromine loss test to distinguish between loss from sunlight vs. other losses. Do that first before making any other conclusions. Let us know these two losses (overnight with no sun exposure vs during the day with sun exposure).

 

[BobbyR]

Re: Need help with bromine pool

OK, so I loaded up the feeder with tabs last night and turned it to max and ran it overnight for 12 hours. Br level was 1ppm at the start. The pool was last shocked with oxidizer 3 days ago. Just measured this morning and it's way up at 10 ppm so I'm definitely meeting the demand with the feeder stuffed full and set to max. I've turned off the pump and I'll measure again later today to see what happens. Again, if the Br reserve is very slow to deplete, why is it necessary to continually add to it once it is established? It's costing $200 a month for bromine at this rate. Why not just use low cost Cl tabs in the feeder to oxidize the Br already there? By the way, the good news is that the pool water is sparkling clear with no visible problems. Ph is 7.8 and TA is 120.

 

[chem geek]

Re: Need help with bromine pool

Again, you haven't proven anything because 1) you haven't compared quantities of the rate you are adding with the feeder vs. the amount of oxidizer you add and 2) you didn't do the tests I asked you to which would compare the bromine loss rate during the day in sunlight vs. overnight with no sun. Also, you aren't doing your two situations in the same way -- you are adding your oxidizer in one dose having the level go up and then seeing it go down while with the bromine tabs you are feeding it continually. What happens to the level when you stop feeding with bromine tabs? Does it drop as quickly as the bromine level did when you used an oxidizer? If so, then the issue has nothing to do with any bromide bank since the bromine tabs would be introducing at least half bromine (if using BCDMH tabs; or all bromine if using DBDMH tabs).

What is the oxidizer you are using for shocking? If it's chlorine, what kind (chlorinating liquid, bleach, Dichlor granular, Trichlor granular, Cal-Hypo)?

If you found that adding a chlorine oxidizer at night was able to show bromine overnight but it went away during the day while if you did the same experiment with bromine tabs and found that the bromine level held both day and night and if you have no Cyanuric Acid (CYA) in the pool, THEN that would show that you don't have a bromide bank and that any added chlorine is remaining as chlorine and getting broken down by sunlight.

With your FAS-DPD kit I can have you determine whether you have a bromide bank, but please do the overnight vs daytime loss tests as well. Bromine does break down during the day, but not as quickly as chlorine if no CYA is present. And the real comparison is seeing if there is a difference in the loss rate after you use an oxidizer vs. using tabs.

 

[BobbyR]

Re: Need help with bromine pool

Yes, I know I haven't done the tests as you prescribed. There obviously hasn't been time. Just updating on current state of affairs. We do at least know that the Br level will come up without shocking by cranking the feeder way up. That's at least something and it's important because we are going away for a week and I want to be sure the pool will be ok while we're gone. I'll do the full tests when we return. Thanks for your help.

 

[BobbyR]

Completed the conversion of my pool to Chlorine from Bromine

Further to the above, I wanted to convert from Bromine to Chlorine because Bromine tabs were costing me a fortune. I was also finding it difficult to maintain bromine at effective levels in a heated pool. Frequent shocking was required with MCP at additional and significant expense. Bromine, for me at least, had turned out to be an expensive and marginal way to sanitize my pool. After discovering this site the BBB method caught my eye; I decided to convert to chlorine. I read all the threads about the difficulties involved and was prepared to drain the pool if necessary (water is not terribly expensive here) but decided to experiment first to see what would happen if I simply started to use Chlorine instead of Bromine.

First step was to ensure that I had nothing growing in my pool. Though it appeared to be pretty clean there was a persistent problem maintaining the bromine level. To accomplish this I shocked my pool with liquid chlorine for a solid week, morning and night, using copious quantities of 12% liquid chlorine. I don’t have a proper test kit as you can’t get it in Canada but my chlorine/bromine was sky high for a week. I brushed all the nooks and crannies and there was no visible algae anywhere so I was good with it. Even if there had been before, I’m sure there was now nothing growing in my pool.

Next, I started adding liquid chlorine every morning and night, experimenting with the amounts required to maintain 4 to 6 ppm of Br using the Bromine scale on my test kit. I quickly found that I couldn’t maintain day time levels with a single dose although the overnight levels would hold with negligible losses. At that point I decided to add some CYA to see if that would help. I added CYA using a sock in the skimmer to bring the level to around 35ppm. I have no way to actually measure this but the arithmetic was straight forward. With the CYA in the pool the CL/Br levels held during the day and less was required than before to maintain the desired levels. During this time I had a couple of upward swings in pH requiring the addition of muriatic acid (extremely effective). Also had to adjust TA to get it up over 100. Eventually pH stabilized at 7.6 and TA at 110. (as recommended here, I used grocery store Baking Soda at a 30% savings over pool store TA adjuster. Bonus!). Surprisingly, I think all of what happened to this point was pretty much what you’d expect with just chlorine in the pool and no bromine.

At this point I started to realize that liquid chlorine, for all its benefits, is just too hard to handle (for me). After ruining a pair of jeans, some socks and a couple of shirts it was clear that I just can’t work with the stuff without splashing and spilling and the dangers of tracking it into the house and ruining carpets and floors was looming. We also are away a lot in the summer at our cottage. The only option was chlorine pucks. Faced with the alleged dangers of explosion if I put them in my brominator, I purchased a floater and loaded it up. The floater would wander over to the skimmer where it stayed all day but I had to keep the pump running 24 hours a day to maintain the levels. Before adding a second floater I revisited the idea of using the old brominator. By then it had been running empty for a month and was squeaky clean and smooth inside. I concluded there was no danger of explosion and loaded it up with chlorine pucks. This worked perfectly and I now only have to run my pump 8 hours overnight when electricity rates are lower. To avoid CYA build up I am backwashing weekly, lowering the water by a half inch or so each time. As I am only consuming a couple of pucks per day overall, I figure this will prevent buildup but I realize that I will have to confirm this at some point with some CYA measurements.

In conclusion, although I am still technically running a bromine pool, it really doesn’t seem to matter much. The water is sparking clear and odorless and I keep the pool at 87F so it is very warm. With the weekly back washing I will eventually eliminate the bromine reserve but I'm not sure how I'll even know when this has happened. In practical terms, there does not appear to be any significant observable differences between the br/cl hybrid pool and a pure chlorine pool. The disadvantage is that I can’t really use the pool calculator with any certainty for chlorine usage. It’s basically trial and error, at least until the bromine is gone.

Hopefully my experience with this will be of help to others in the same situation who are tired of spending hundreds of dollars a year on bromine tabs that don’t even work very well compared to chlorine. Thanks to TFP I am now free of that financial burden and have a cleaner pool to boot.

In conclusion, I have converted from bromine to chlorine without emptying my pool (and without blowing myself up) and it seems to be working very well at a fraction of the cost.

 

[linen]

Re: Bromine is pretty confusing alright but it does work wel

I don’t have a proper test kit as you can’t get it in Canada

Not cheap, but you can get it: http://piscines-apollo.com/cubecart/test-kits/k-2006.html

Two 3-inch (~8oz) pucks per day will add 20 ppm cya per week. You will need to drain/refill 30% of your pool per week to keep you cya level at 50 ppm. You will likely also need to raise ph and TA regularily since trichlor pucks are very acidic. This is not a reasonable/sustainable approach.

 

[BobbyR]

Re: Bromine is pretty confusing alright but it does work wel

I'll order one when we're down in Florida for the winter. Too expensive up here. I'll get by without it for what's left of the summer. pH hasn't been an issue. It hasn't changed since I brought it down with the acid and raised the TA. As for the CYA issue, that problem would arise for anyone using pucks would it not? It's not just because I've converted from bromine. Perhaps I've got the brominator set too high and could dial it back a bit but, with the water so warm, they melt away pretty quick. 30% of my pool would be almost 8,000 gallons. Every week? Good grief. I'll take some water over to the pool store and have them run a CYA test to see how it looks.

 

[linen]

Re: Bromine is pretty confusing alright but it does work wel

As for the CYA issue, that problem would arise for anyone using pucks would it not?

Yes, it is the most common problem we see with new members.

30% of my pool would be almost 8,000 gallons. Every week? Good grief.

Yep that is right. With that said, I am not an expert, but I think it is likely you still have a bromine pool, and the chlorine is still converting the bromide to bromine.

 

[BobbyR]

Re: Bromine is pretty confusing alright but it does work wel

Yes, I'm sure it's still a bromine pool but how does that matter? Chlorine pucks are widely used and people are not having to pump off tons of water every few weeks. What am I missing here?

 

[linen]

Re: Bromine is pretty confusing alright but it does work wel

Chlorine pucks are widely used and people are not having to pump off tons of water every few weeks. What am I missing here?

Puck users eventually almost always have to do a partial drain/refill unless they have a leak or do a significant drain for winter. Our recommendations on here are to ensure a pool remains algae free. Many puck users are right on the precipice where they could easily have water issues.

 

[chem geek]

Re: Bromine is pretty confusing alright but it does work wel

Two 3" Trichlor pucks per day, if they are 8-ounce weight pucks, in 23,500 gallons would be 4.7 ppm FC per day and 2.8 ppm CYA per day. That's a very high chlorine loss rate so may very well mean you are creating more bromine and that bromine is not protected much by CYA in the water. The weekly CYA rise would be 20 ppm as was noted and that is very high.

 

[BobbyR]

Re: Bromine is pretty confusing alright but it does work wel

I'll reduce the setting on the brominator and see how it works. I really have no feel for how many chlorine pucks I should be using as I have no experience with them. I may be using way more than I need. What would be a reasonable burn rate for a my pool kept in the mid 80s?

 

[chem geek]

Re: Bromine is pretty confusing alright but it does work wel

Start with half that rate or one puck per day. Then measure your bromine level to see where it ends up. You only need around 4 ppm bromine since it's not moderated in strength by CYA. You may even be able to go lower, but why don't you start by targeting 4 ppm bromine (around 2 ppm FC if you use a chlorine test without converting units). If your bromine level is rising, then you are adding too much. As you noted, you are only losing bromine during the day so you should be having your pump on and dosing during the day and not at night. See what happens between a reading in the morning and night -- you should have roughly the same reading if you have things set properly since you said there was very little loss overnight.

Even so, you'll still be increasing CYA by nearly 40 ppm per month so would require an 18% weekly water dilution to maintain 50 ppm CYA. Of course, so long as the pool remains a bromine pool, the CYA level won't matter so much.

 

[BobbyR]

Re: Bromine is pretty confusing alright but it does work wel

Thanks. Maybe I'll rethink the pucks and go back to liquid Chlorine when we are at home. I just cannot see dumping that much water down the drain every week.

 

[BobbyR]

OK, so I rushed right out and had my water tested this morning to get a reading on this CYA issue as I was a bit concerned. I had them test it as a Chlorine pool which includes the CYA test.

Results:
Free Chlorine - 1.25
TA - 110
pH - 7.5
CH - 220
CYA - 40 ppm

Results for Cl, pH and TA tie almost exactly to my home test kit results so that's a good sign.
Free chlorine is a bit low because I left the pump off overnight to switch from overnight to daytime pumping as per chem geek above.
CYA is 40 ppm, adjusted higher than my initial load (~35ppm) because of puck usage over the past month, and lower by the amount I've back washed out.

Pool store did not recommend any corrective measures (for what that's worth).

I really don't know how to reconcile these results with the earlier comments in this thread regarding CYA build up but there seems to be something missing in the analysis because I have not back washed anything remotely close to 8000 gallons/week since starting the pucks. I'm going to continue using them for now and closely monitor the CYA. I will post back with my progress although the pool season is drawing to a close up here.

Unfortunately.

 

[linen]

cya testing is one that pool stores get more wrong than right. With that said, as chem geek mentioned above, since your pool is still a bromine pool, you may not need to worry about cya now. At some point though, you will need to deal with it.

 

[BobbyR]

It is now a year since I last posted in this thread but, for continuity, I am bumping the thread to provide an update, rather than open a new one. Last year I converted from Bromine to Chlorine without draining any water and without attempting to somehow allow for or compensate for the residual bromine in the pool. I was prepared to drain the pool if required but thought I'd try using chlorine first, managing the pool as if it had no bromine in it. At the end of last year I was using chlorine pucks because I had initially had some problems handling the liquid chlorine, spilling it on myself and generally making a mess. The pool was clean and free of algae at the end of the year but, as you can see from the later posts, there were concerns with the potential buildup of CYA from the use of the pucks. Advice here was that the use of pucks would require backwashing unworkably large amounts of water on a regular basis so, when I opened the pool this year, I decided to retry liquid chlorine. Over the winter, while in Florida, I acquired a TF-100 test kit so I was better able to test the water to see what was happening. When opening, I ignored any residual bromine in the water, managing as though it was a chlorine pool. When the cover came off the pool the water was dirty so I shocked it using the SLAMM instructions on this site, adding no algaecide. In a few days the pool was clean and showing no overnight FC loss and I made the required adjustments to pH using muriatic acid and to pH by adding baking soda. CYA was already at 50 ppm from last year so I just went with it, adding about 3 litres of liquid chlorine a day to maintain the FC at about 3 ppm. I'm very pleased with the results as my pool has never been as clean and sparking as it now is. I have not shocked the pool even once as it hasn't needed it and the water has been very stable.

My conclusion here, for the benefit of those with bromine pools wanting to convert, is that the conversion is easy; don't get hung up on the bromine issue. Just pretend there's no bromine in your pool and proceed with the instructions on this site for managing with liquid chlorine. I can't say that there is no difference between this approach and a fresh fill, only that it's easy to get good results without a fresh fill. One thing I found was that I needed a lot of chlorine to reach and maintain the recommended 4-6 ppm FC with 50 ppm CYA but I also found, with experimentation, that I didn't need that high a level to maintain clean water and no CC. I now keep it between 2 and 3 ppm with perfect results. Liquid chlorine costs a little more than using pucks and I am using more chlorine than I thought I'd need. I pay $6 for 10 litres of 12% chlorine and I use 3 litres a day so it's costing me $50 to $60 per month. I haven't found any cheaper source than this around here. Pucks would be about $30 a month but I'd be using more water and there is a cost to that. In any case, what I'm doing is still a lot cheaper than what I was doing before, spending a fortune on bromine tabs, algaecide and pool store baking soda at twice the grocery store price.

For the record, my water tested this morning as follows:

FC 2 ppm (forgot to add chlorine last night as I usually do)
CC 0 ppm
TA 110 ppm
ph 7.8
CYA 50 ppm

Hope this helps anyone out there who is tired of spending a fortune on bromine and wants to convert to chlorine as recommended on this site.

ps I switched my hot tub to chlorine as well and it is pristine, much nicer than with the bromine tabs in the floater. There is no odor at all, something I never achieved with the bromine tabs.

 

[chem geek]

If you still have bromide in the water, then the chlorine you add is making bromine and that breaks down in sunlight faster than chlorine with CYA so may explain why you are using more chlorine than usual. It also may explain why you can have a lower FC target for your CYA level since if it's really bromine then it is not moderated in its strength by the CYA. Eventually though when the bromide is used up through water dilution, bromine outgassing, etc. you may find you need a higher FC level to prevent algae growth, but your daily FC loss should get slower as well.

Glad to hear your spa is also working well for you.

 

[BobbyR]

Thanks Chem Geek. I think your analysis is correct and, if so, my chlorine costs should drop a bit. We'll see next year. I'm closing the pool on this coming Friday.