Thread: SWIMMING POOLS | Bromine Questions 01

SWIMMING POOL FORUM | The Bromine Bank



To B . . .

. . . or not to B

I recently posed the following questions, about Bromine Bank, Cyanuric Acid and Bromine Test Reagents to Alan at http://www.askalanaquestion.com/

Dear Alan
I would be extremely obliged if you could help out with some important issues about Bromine sanitizers.

The Background: I live in the Costa Blanca area of Spain, which has a climate similar to Florida and practically every home has an in-ground, tiled, concrete swimming pool.
Most properties are rented for at least 3 months each year. Consequently, there is very high bather load during this summer seasons and considerable bather abuse.
Water is very expensive.
Sometimes we have drought situations, when water has to be purchased for filling pools in tankers. Drained down pool water also has to be removed by tanker.
Most pools are sanitized with TriChlor (Tablets and Granules) and shocked with liquid (Sodium Hypochlorite).
Due to the need to conserve water, backwashing tends to be light, we get an increase of Cyanuric Acid of 80 – 100 ppm per year and many pools are running on 300 ppm CYA or more.
We all use an algaecide, usually copper-based chelated liquid sometimes just crude copper sulphate.
Alan Commented: Copper sulfate is not recommended for use in swimming pools. Concentrations over a few tenths of a PPM, can cause staining, green hair and fingernails, especially if the pH is high. Copper algaecides are formulated to make these events less likely and should to preferred way to add copper.
As you can imagine, with high CYA, even free chlorine in excess of 5ppm and regular shocking does not work.
Many of us use a 2-part Bromine system, which seems to overcome all of the problems. We use Sodium Bromide for the base and oxidize it with TriChlor, Sodium Hypochlorite or Monopersulphate. This system works well but it has developed rather by “trail and error” as there is no technical support available locally.

Establishing and Maintaining the Bromine Bank: My understanding is that the Bromine Bank should never be less than 15 ppm, so I aim at 25 ppm. I add 4 Kgs to start the pool off (50,000 litres) and then 1 Kg every spring, on the basis that I have a 25% water changeover.
I have been doing this for so long that I cannot remember where I got it from in the first place and there is a great variance of opinion regarding the respective amounts.
Could you please explain how we calculate this properly?

Alan Answered: Once you establish a bromide bank, of 25 PPM or higher, additions of any form of chlorine will convert the bromides into hypobromous acid. The higher the level of bromides, the faster the reaction will take place.
1 kg of sodium bromide, added to 50,000 liters of water, will produce a sodium bromide level of 20 PPM.
The use of bromine, in an outdoor setting does present a problem. The Sun's UV rays will slowly destroy the bromine. There is no chemical, such as cyanuric acid, which will help protect the bromine from the UV degradation.
How much chlorine will be required on a daily basis will depend on the type of product being used, pool usage, water temperature and weather factors. Using liquid chlorine adds no problematic byproducts and works quickly. Trichlor does contribute cyanuric acid and is slow to dissolve. High level of cyanuric acid could lead to skin irritation, in sensitive individuals.
Non-Chlorine shock adds no problematic byproducts, works quickly, but will not generate as much bromine on a weight basis. In the US, bromine tablets are the principle means of adding bromine. This 2-part approach, while feasible, is not used in outdoor pools.

My further question RE: The Ideal Bromine Bank for an in-ground pool: You said "Once you establish a bromide bank, of 25 PPM or higher, additions of any form of chlorine will convert the bromides into hypobromous acid. The higher the level of bromides, the faster the reaction will take place."
You also resolved the dosage required, recommended a kit to test the Bromine Bank and we do understand the fragility of Bromine in strong UV light.
Therefore -
1. We need to be sure that we have enough Bromine but don't want to "go over the top". What ideal concentration of Sodium Bromine (in ppm) would you reccomend?
2. I understand that there is now a stabiliser for Bromine. Do you know anything about this?

Alan Answered: How much bromine is produced depends on the amount of chlorine or oxidizer added. The amount of sodium bromide does not play a role, so long as there is a minimum amount present. I suggest 25-100 PPM. Higher levels should not present a problem, other than cost.
There is no stabilizer for bromine that I am aware of.

Testing for pH: My understanding is that some Phenol Red test kits are extremely inaccurate when used with a Bromine pool because they provide a brownish colour, which could be interpreted as high pH when the reverse is the case. The only reliable Phenol Red that I have found locally is Taylor but there may be others.
Would you like to comment on this?

Alan Answered: The use of phenol red testing materials can present a problem, if the reagents do not contain a high enough content of a chlorine/bromine neutralizer (usually sodium thiosulfate). The lack of the sodium thiosulfate allows the bromine to react with the phenol red, producing brom phenol purple, which makes it appear the pH is very high. This "purplish" color has no relationship to the actual pH. Most quality testers are made with sodium thiosulfate present in the phenol red liquid or tablet. However, if the bromine level is very high, it may overwhelm the sodium thiosulfate present and produce an erroneous or misleading result. Adding a drop or two of a separate chlorine neutralizer test solution, prior to use of the phenol red, should discharge the bromine and allow for a proper pH reading. All LaMotte testers are formulated with this in mind. I can't speak for other manufacturers, as I don't have the access to the information.

Testing for Bromine Bank: My understand is that there is no known pool-side test for the Bromine Bank except –
a)Your Nose: If you smell chloramines on skin after bathing then it is deficient.
b)Combined Chlorine test: There should never be any at all.
My theory is that, if the Bromine Bank is deficient, both hypobromous acid and hypochlorous acid are formed at the same time, making it possible for chlorimines to develop. However, neither test could be considered positive.
Would you agree with this?

Alan Answered: It is now possible to test for the presence of sodium bromide, with a test strip. For more information go to: www.lamotte.com or www.askalanaquestion.con/the_pool_and_spa_test_strips_store.htm

My further question about the mentioned sodium bromide test strips: On your website you say - "The Insta-Test Sodium Bromide test strips can be used to determine the concentration present, in pools or spas, that are using bromine or have added a product containing sodium bromide. Measures levels from 1000, 1500, 2000, 2500 and 3000 PPM."
We are going to be measuring SB levels from (say) 10 - 100 ppm. Surely these won't be any good but is there another product or a work-around with this one?

Alan Answered: These strips were designed to be used with salt bromine generators, where the expected PPM were in the thousands. Basically there is all you need is for the test to register positive. Even it it rose to 1000 PPM, over time, because of replenishing additions, it would be acceptable.

Excess of Cyanuric Acid: The actual local legal maximum CYA is 75 ppm but even a “commonsense” level of 150 ppm is impossible to maintain without using huge quantities of water.
My understanding is that the free chlorine should be at least 7.5% of the CYA. Consequently 100 ppm CYA requires 7.5 ppm FC otherwise the water is not safe for bathing because the Chlorine will not kill bacteria and virus quickly enough, resulting in a high risk of cross-infection among bathers. Nevertheless, combined with copper-based algaecide, the chlorine does control algae but this is not the point.
My view is that, with an excess of (say) 200 ppm CYA and only 5 ppm FC a potential health hazard to bathers has developed, which should not even be contemplated by a responsible pool technician.
Furthermore, sanitizing properly with Bromine, greatly reduces this risk because Bromine is not affected the same way by the CYA.
Would you agree with this?
Alan Answered: Cyanuric acid does not have the same inhibiting effect on bromine, as it does on chlorine. With chlorine, you are forced to maintain higher free chlorine levels, as the cyanuric acid levels rise. Maintaining a level of free chlorine, at 7.5% of the cyanuric acid content, might be excessive and will be a challenge. I have never seen any reference to this 7.5% figure, as it relates to the problem.
The only way to eliminate CYA is to replace water. That may be impractical during water shortages. Backwashing a filter can be reduced, if the sand is replaced with Zeobrite. Not only will the water quality improve, but backwashing will be greatly reduced.

Resolving Total Alkalinity with High Cyanuric Acid: My understanding is that 30% of the CYA resolves to Cyanurates and these are included with the standard Taylor test for TA. However, cyanurates cannot be considered “buffering” agents and 30% of the CYA has to be deducted for the true TA.
The problem is that there is an anomaly here. We try to achieve a TA of 80 – 120 but with CYA at of (say) 300 (which is about average) the TA should be 180 – 220 and I know for sure with that my pH will go well over 8.0 Whereas, with TA of 120 – 140 it settles down nicely at 7.6 to 7.8 – which would seem about right for Bromine and the water “feels” good.
What are your thoughts of this?

Alan Answered: High cyanuric acid levels do present a TA anomaly, when 30% of the CYA is subtracted from the TA. The pH is always more important that the TA. Always!!! When the pH is in range, is reasonably stable, the water is clear and there are no signs of scaling, there may be no compelling reason to adjust the TA.

Alan Schuster kindly answered the questions.
Alan runs a marvellous website in USA devoted maintaining pools, spas and hot-tubs. You will find everything there that you ever wanted to know – and more.
AskAlan.com | A Resource for Pool & Spa Water Chemistry & Problems, Water Quality and Related Maintenance Issues Information.

There are two good artivles about the use of bromine sanitizers in Costa Blanca -
Bromine Sanitizers for Swimming Pools
The Bromine Schedule

I intend to publish a list of pool cleaners who provide bromine. If anyone is interested please publish details to this thread. You obviously have to join the forum first, otherwise potential customers will have no way of getting in touch with you.

Homefinder

In short, what have we determined by talking to Alan?

Personally I have resolved several doubts I had before but to summarise everything -

• Once the water is a couple of years old there is no valid reason to continue to use chlorine. If bathers want to stop smelling like a bottle of "Lejia" then best to go for Bromine from day 1. For professionals there is no other option because it saves visits, saves valuable water and makes it possible to provide a better service at a lower price.
• We have determined the minimum ppm for the Bromine Bank with virtually no maximum. We know that below 25 ppm it won't work.
• We know that there is now a test for bromine bank.
• We have determined that Copper Sulphate has no practical use as an algeacide for swimming pools due to the danger of staining and green hair.
• We understand the problems cused by testing bromine pools with Phenol Red - and the serious concequences of misreading it.
• When testing for total alkalinity, 30% of the cyanuric acid has to be deducted for the true result. With high CYA the recommended TA (80 to 120) cannot be achieved with the pH in the right range. Consequently the correct TA is the own that provides a stable, correct pH.

A further observation of mine: The use of trichlor causes a slow, but regular, fall to the total alkalinity. Simply testing for pH is not enough because the inevitable result is highly acid (corrosive) water, resulting in serious damage to the tiles, grouting, metal parts etc. bad staining (usually from copper) and irritating water.
Checking and balancing TA regularly is vital.
If Bircarb is used for pH-plus (instead of Carbonate) the TA usually keeps itself balanced for much longer.

Thank you Alan Schuster for patiently answering my numerous emails.

Homefinder