Intellichem Controller Settings

[JamesW]

That dilution formula only accounts for part of the contamination.

If you add CYA or DMH or anything else that you want to keep below specific limits, you have to do the separate calculations for those things as well.

 

[JamesW]

I'm guessing we go through 20 lbs of tabs in about 4 months.

That adds 3.6 ppm DMH per week.

That is only about 1.15 lb per week, which is pretty low.

Are you sure about that number?

20 lbs of tabs will add 26.47 lb of bromine, which is 158 ppm bromine.

4 months is 122 days.

158/122 = 1.3 ppm bromine per day or 9 ppm per week.

I'm diluting 2.5% of the water weekly (500 gallons of the 20,000 gallon pool volume), how does this change things?

Assuming a 3.6 ppm increase per week, the equilibrium is 144 ppm DMH.

If you use tabs, 20 lbs of tabs will add 10.612 lb of DMH, which is 63 ppm DMH and 50 ppm of sodium bromide.

2.5% of 145 = 3.6 ppm.

So, you remove 3.6 ppm on dilution and add 3.6 ppm back during the week before the next dilution.

128.13/241.47 = 53.06% DMH.

20 lbs of tabs will add 26.47 lb of bromine, which is 158 ppm bromine.

The percentage adds up to more than 100% because the chlorine is counted as bromine because the chlorine converts into bromine and the bromine counts double since it is measured as Br2.

1,3-Dibromo-5,5-dimethylhydantoin (DBDMH) can have an available bromine content of 111%.

 

[JPMorgan]

This all gets pretty complicated... especially for a volunteer pool maintenance guy! I think this is the course I will settle on and my reasons:

1. Changing the present system is complicated. That will involve new plans (required by the state), additional fees, etc. In addition, if things go awry (and they always do), I'm on the line for recommending the changes. Not sure I want that responsibility.
2. My experience has been that HOAs are "conservative" and don't like to spend money without compelling reasons to do so. Trying to convince them to spend money to change the bromine system on a low use pool will be a difficult task. They already think the pools are too expensive!
3. The current set up has been in place for at least 8 years and (as far as I know) there have been no complaints.
4. One thing I learned recently is that the practice has been to drain and re-fill the pool annually. I was told this by the guy who took care of the pools here previously. I wasn't aware of that. Our pool company also recommends an annual refill. I'm sure this is due to all the issues that have been noted above, i.e., DMH, DBPs, etc.
5. With an annual re-fill, along with weekly dilution of about 500 gallons (and considering we have a very low use pool), I'm convinced that we can avoid any serious issues with the present set up. At any rate, this has been the established practice here, so the safest course of action for me (I think) is to follow what has been the established practice and also what the pool company recommends.

I rarely drained and re-filled water when I had my own residential pool, but I was using liquid chlorine. My intention here was to try to save the HOA the cost of annual pool re-fills, but by going down that road I assume a lot more responsibility and risk. While I'm sure there are ways to improve the present set up, I have come to the conclusion that it is just not worth the effort. However, I have learned at lot and I appreciate all the input. Thanks.

 

[JamesW]

If you drain 2.5% of the water each week and add 3.6 ppm DMH per week, the level will slowly work its way down to 144 ppm of DMH.

If you start at 200 ppm, 2.5% is 5 ppm, so 200 - 5 + 3.6 = 198.6 after 1 week.

198.6 - 198.6(.025) + 3.6 = 197.235 ppm after 2 weeks.

197.235(0.975) + 3.6 = 195.904 ppm after 3 weeks.

144(0.975) + 3.6 = 144 ppm.

If you start with a fresh fill and 0 DMH and add 3.6 ppm DMH per week and remove 2.5% of the water each week, the level will slowly increase to 144 ppm.

So, either way, the level will eventually get to 144 ppm.

So, basically it will take an infinite amount of time to eventually get to 144 ppm because the amount of DMH removed on each dilution is lower each time.

I would say that a DMH of 80 should be the maximum limit, but I do not have a good reason for that specific number.

Mostly, it is using the same rule as CYA, which I suspect is probably the best rule without better information to go on.

To have an 80 ppm equilibrium at 2.5% dilution per week requires a DMH addition limited to 2 ppm per week.

To have an 80 ppm equilibrium with 3.6 ppm DMH added per week requires a dilution of 4.5% per week, which is 900 gallons.

80 x 0.955 = 76.4.

76.4 + 3.6 = 80 ppm.

If you can supplement with liquid chlorine, then the amount of DMH added will be reduced and you can get the levels lower faster.

 

[JPMorgan]

So, basically it will take an infinite amount of time to eventually get to 144 ppm because the amount of DMH removed on each dilution is lower each time.

If you can supplement with liquid chlorine, then the amount of DMH added will be reduced and you can get the levels lower faster.

I started shocking the indoor pool every week recently and am now planning to do it every other week. The problem is that I can only keep bromine at 20 ppm for about 24 hours because residents want to use the pool, so after 24 hours of maintaining 20 ppm, I am adding a neutralizer to bring it down to 10 ppm or less so the pool can be used. (State regulations say the pool has to close if bromine is over 10 ppm.) This procedure essentially shuts off the bromine feeder for several days while the bromine level is high and gradually drifts lower.... then the brominator starts feeding again. I know now that this is not ideal because during this time a "toxic stew" is being created in that bromine feeder. So... my plan is to fill the feeder only about 1/2 way (or less) and monitor it closely over a 2 week period. When the bromine feeder is basically empty, it seems that would be the best time to shock the pool, so there is very little bromine sitting in that feeder during shock and for a few days after. Once, the bromine level drifts lower I will fill the feeder again.

I know that I could hand feed liquid chlorine in the pool for a period of time to reduce DMH at a faster rate (with the bromine feeder empty, of course). However, that kind of defeats the whole purpose of automating our pools. For two seasons I manually dosed liquid chlorine in our outdoor pool until I was able to convince the HOA to install a liquid chlorine feeder (which we did this past summer). If they had decided against doing that work I would have "retired" from pool maintenance here, but I was able to make a strong case for it and they went along.

Once I get a good handle on how many pounds of bromine we use over a two week period I should be able to manage how to fill the feeder so that it is almost empty when I shock the pool. That will reduce the amount of bromine being introduced into the pool, as it will take a few days to drift down from 10 ppm to 4 ppm. I will also continue with regular dilution (500 gallons per week). My goal is to keep the DMH in check until this summer, then have the pool drained and refilled with fresh water (while the outdoor pool is open). Then, continuing these procedures, I will monitor things closely to see if we can go one year only using 50-60 lbs. of bromine tabs (about 5 lb.s per month)... and then start an annual drain and refill of the pool during the summer. Even though this will cost about $2,000 annually, it will be hard for the HOA to ignore that advice since...

• this has been the previous practice (even though most are not aware of this)
• the pool company recommends it
• we know that DMH accumulates in a bromine pool over time rendering the bromine less effective, but we are not able to test for it.

With all that information they would be taking a big risk to ignore that advice.

 

[JamesW]

I would probably keep the bromine level at about 9 ppm continuously rather than shocking to over 10 ppm.

I would reduce the use of tabs as much as possible and supplement with liquid chlorine.

I would switch to SWG to make everything much easier and eliminate the annual drain and refill.

Just because something has always been done a specific way does not mean that that way is the best way.

 

[JPMorgan]

I would probably keep the bromine level at about 9 ppm continuously rather than shocking to over 10 ppm.

I would reduce the use of tabs as much as possible and supplement with liquid chlorine.

I would switch to SWG to make everything much easier and eliminate the annual drain and refill.

Just because something has always been done a specific way does not mean that that way is the best way.

• I'm shocking the pool with liquid chlorine. Isn't raising bromine to the minimum shock level per Pool Math (20 ppm) important to eliminate DBPs?
• Wouldn't maintaining the pool at 9 ppm bromine (if we are going to continue to use tabs) just increase the DMH in the water? I like to keep it around 5-6ppm
• I'm going to ask our pool company about converting to SWG and share your recommendation re SWG with our HOA. Would drain and fill ever be necessary with a SWG system? Aren't there issues with controllers sometimes when using a SWG system?
• Yes... I understand about making changes. It just may be the least risky and less frustrating way (for me) to move forward and make sure the pool water stays relatively healthy.

 

[JamesW]

Isn't raising bromine to the minimum shock level per Pool Math (20 ppm) important to eliminate DBPs?

Not really.

Wouldn't maintaining the pool at 9 ppm bromine (if we are going to continue to use tabs) just increase the DMH in the water?

I mean using liquid chlorine.

Would drain and fill ever be necessary with a SWG system?

Not if you do regular dilution based on swimmer hours.

Aren't there issues with controllers sometimes when using a SWG system?

Not any more than with any type of feeder.

ORP can work with very low CYA.

You can get a true chlorine sensor that is not affected by CYA.

You don't even need a controller if you can find a percentage setting that keeps the FC in the target zone.

UV can help with stabilizing the FC levels.

 

[JPMorgan]

Not really.

Can you explain a bit more? I thought that shocking to eliminate contaminants in the water involved raising the sanitizer to the SLAM level and keeping it there for a period of time. Pool Math tells me I need to raise to 20 ppm.

I mean using liquid chlorine.

Okay, but this would involve me manually dosing the pool once or twice a day (at least until we install another type of system) and I don't want that responsibility any longer. I did that for 2 seasons with the outdoor pool. Relying on one guy to manually sanitize the pool every day is not a good way to run a "public" pool!

 

[JamesW]

Pool Math tells me I need to raise to 20 ppm.

For bromine?

Raise it to 20 based on what, how often?

SLAM is based on a FC/CYA ratio of about 40%.

There is no real SLAM protocol for bromine.

If the DMH is 200 ppm and you are shooting for 40%, then that is a bromine level of 80 ppm.

In my opinion, keeping it higher continuously will be better than periodic "Shocking" followed by chlorine neutralizer.

A SLAM might be needed if you get algae or combined bromine results.

However, these are a clear indication of insufficient levels being maintained.

Disinfection byproducts (DBPs) are fairly persistent and they might not go away with normal chlorine or bromine levels or "SLAM" levels.

In my opinion, the biggest issue is the DMH, which needs to get reduced by at least half immediately.

Dilution can help with Disinfection byproducts (DBPs).

UV might help with Disinfection byproducts (DBPs).

I am adding a neutralizer to bring it down to 10 ppm or less so the pool can be used.

What are you using for neutralizer?

 

[JamesW]

I thought that shocking to eliminate contaminants in the water involved raising the sanitizer to the SLAM level and keeping it there for a period of time.

How are you determining when a "SLAM" or "Shock" is required?

Are you just doing it periodically as a matter or routine or to address specific problems like algae or CCs?

 

[JPMorgan]

How are you determining when a "SLAM" or "Shock" is required?

Are you just doing it periodically as a matter or routine or to address specific problems like algae or CCs?

Initially I was doing it to to address algae and that has cleared up. Then, I thought that as a preventative measure I should shock every other week. As I mentioned above, when I do the test for CC the water sample becomes clear after adding two drops of R-0003 reagent, so that means less than .9 combined bromine, correct (.45 x 2)? So.... no need to shock at that level.... just maintain bromine level on the high side and keep doing regular dilution? State regs say that bromine should be maintained between 2 and 8 ppm with minimum of 4 ppm if temp is above 85 degrees and that the pool should be closed immediately if bromine level is 10 ppm or greater. Given those criteria, would you shoot for maintaining at 8 ppm?

 

[JPMorgan]

For bromine?

Raise it to 20 based on what, how often?

I was using Pool Math (which only does calculations for FC based on CYA levels). Pool Math tells me SLAM level is 10 ppm FC when no CYA is present, so I doubled that for bromine to get to 20 ppm bromine. I think you are saying this is not necessary at all unless algae is present or CC is above 1 ppm (though I understand that combined chlorine and combined bromine are not the same).

 

[JPMorgan]

A SLAM might be needed if you get algae or combined bromine results.

How high should I raise bromine level in either situation above? Am I correct that combined bromine is less than .9 ppm if the water sample clears after 2 drops of R-0003? If I get higher levels of combined bromine when testing what formula would I use to determine how high to raise the bromine level?

 

[JPMorgan]

What are you using for neutralizer?

sodium thiosulfate

 

[JamesW]

The TFP Methodology is designed for outdoor, residential, chlorine pools.

You have an indoor, commercial, bromine pool.

Pool Industry Practice is to maintain inadequate chlorine and then periodically “Shock” as a way to catch up.

The TFP Methodology is based around the FC/CYA relationship, which is designed to provide adequate chlorine and avoid routine “Shocking”.

SLAMMING is designed to be used only to respond to issues like algae or CCs, which mostly only happen when someone not maintaining adequate chlorine.

There is no equivalent Br/DMH ratio rule because we do not know the ratio and we do not have a test for DMH.

If you use the same ratio for bromine as for chlorine, you will maintain a minimum Br/DMH of 7.5%, with a target of 10% and SLAM level is 40%.

You have to have a way to determine DMH levels such as calculating from the amount of tabs added from a fresh fill.

I would put a limit of 80 ppm DMH.

One reason is because you are under commercial regulations that require you to limit the Bromine level and you won’t be able to maintain the 10% ratio once the DMH exceeds 80 ppm.

If you see algae, then you know that you are not maintaining adequate bromine levels.

If you do not pass an OCLT, then you know that you are not maintaining adequate bromine levels.

If you see Combined Bromine, then you know that you are not maintaining adequate bromine levels.

Outdoor pools have UV, which helps break down CCs.

In my opinion, indoor commercial pools should usually have UV as part of their system.

In my opinion, a SWG would probably be the best choice.

 

[JamesW]

If we assume a DMH level of 200 ppm, then there is no way to maintain adequate bromine levels and stay within the state mandated regulations.

The best you can do is keep the bromine as high as legally possible with some margin to avoid going over the legal limit.

Dropping the DMH below 80 ppm would allow you to maintain an adequate level without weekly "Shocking".

Do routine OCLTs to see if you are maintaining adequate bromine.

You can get tests for DBPs if you are concerned about those.

Does your Health Department require testing for bacteria or DBPs?

The below is for drinking water.

Total trihalomethanes (TTHMs) include chloroform, bromoform, bromodichloromethane, and dibromochloromethane.

The Maximum Contaminant Level or MCL for TTHM is 80 µg/L (equal to 0.080 mg/L).

Haloacetic acids (HAA5) include many compounds; currently, five are included in the drinking water standard: monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid.

The MCL for HAA5 is 60 µg/L (equal to 0.060 mg/L).

Monitoring for DBP involves testing for two types of DBP at the same frequency: total trihalomethanes (TTHM) and five haloacetic acids (HAA5).

Be sure to order test kits from drinking water testing laboratories to cover both types of DBP, and follow the sample collection procedures carefully.

Disinfection Byproducts (DBP) | Department of Environmental Conservation

dec.vermont.gov

https://www.aquaticsintl.com/facilities/maintenance/the-abcs-of-dbps_o

 

[JPMorgan]

Does your Health Department require testing for bacteria or DBPs?

No

 

[JPMorgan]

Do routine OCLTs to see if you are maintaining adequate bromine.

What bromine level do I start the OCLT? For FC, I believe TFP says < 1 ppm loss on OCLT is acceptable. What overnight loss should I be shooting for with bromine? If the loss exceeds the acceptable level, then what do I raise the level to until I get the desired result?

 

[JamesW]

What overnight loss should I be shooting for with bromine?

Ideally, as close as possible to 0.

1 ppm FC is 2.25 ppm Br, so maybe use 2 ppm Bromine.

If the loss exceeds the acceptable level, then what do I raise the level to until I get the desired result?

I would avoid going over 10 ppm as this causes the use of thiosulfate, which costs money, wastes bromine and adds sulfates.

If you need to go over 10 ppm, then the DHM is too high and needs to be reduced.