Do high chlorine levels around 28 PPM during SLAM have a chance to damage pool equipment?

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M

Mayday

Member
Jul 6, 2024
20
Jacksonville, FL
Pool Size
12000
Surface
Plaster
Chlorine
Salt Water Generator
For SWG pools, it is recommended to keep the stabilizer level around 70, which means if you need to shock, you need to go up to 28 PPM of chlorine. What impact does that high of Chlorine levels have on the pool equipment, especially if you maintain it for a day or two as the SLAM may require?

It's hard to measure such high Chlorine levels accurately even with the T-2006 kit, and it's difficult to measure exactly how much I am putting in (my Chlorine jugs are 2.5 gallons) so I am just worried about it causing damage if I go overboard a bit.

Not that the pool guys care, they used to just dump in the entire jug when I used them...
 
Your equipment will be fine at SLAM FC levels.

To be clear, a SLAM Process make only take a few days in one pool, but possibly weeks in another. It's not just a one or two day process. There are specific exit criteria that must be met to successfully complete the SLAM Process.
 
Mayday said:
For SWG pools, it is recommended to keep the stabilizer level around 70, which means if you need to shock, you need to go up to 28 PPM of chlorine. What impact does that high of Chlorine levels have on the pool equipment, especially if you maintain it for a day or two as the SLAM may require?

It's hard to measure such high Chlorine levels accurately even with the T-2006 kit, and it's difficult to measure exactly how much I am putting in (my Chlorine jugs are 2.5 gallons) so I am just worried about it causing damage if I go overboard a bit.

Not that the pool guys care, they used to just dump in the entire jug when I used them...
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Like said above, you can safely swim during the SLAM so it’s also safe for equipment.
 
Bperry said:
Like said above, you can safely swim during the SLAM so it’s also safe for equipment.
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It's fine to swim in water that has 24 PPM Chlorine? Are there any sources to back that up, besides posts here at TFP? Everywhere I look on the internet says that level is too high.
I understand all three posts here said the same thing, but everywhere else those levels are not recommended for swimming.
 
Mayday said:
It's fine to swim in water that has 24 PPM Chlorine? Are there any sources to back that up, besides posts here at TFP? Everywhere I look on the internet says that level is too high.
I understand all three posts here said the same thing, but everywhere else those levels are not recommended for swimming.
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That's because none of the other sources understand the FC/CYA relationship or take the CYA level into account.
And those sources are stuck in the 1980's 'science'. TFP uses current science and backs it up with thousands and thousands of TFP members who follow the TFP methodology successfully.
 

Pool Water Chemistry

This thread presents my findings so far on pool water chemistry including the following: More Accurate Calcite Saturation Index (CSI) to replace Langelier Saturation Index (LSI) Calculation of ppm HOCl (disinfecting chlorine) at various levels of Total Free Chlorine (FC) and Cyanuric Acid (CYA)...
www.troublefreepool.com www.troublefreepool.com
 
The amount of “active” chlorine in a pool with 70 CYA is not the full 28ppm you’re imagining. The chlorine is being chemically held by the CYA and only being released as the free chlorine gets consumed by the organic material or algae in the water.

I’m sure the other experts will give you the exact, mathematical proportions, but 28ppm chlorine at 70 CYA is the equivalent of a much smaller amount of chlorine with 0 CYA.

The difference is, with lower chlorine levels in a pool with 0 CYA, the organics will consume that chlorine quickly and there won’t be any more left to continue fighting, hence continued algae.

But with higher levels of chlorine in the water at 70 CYA, the organics consume the chlorine, CYA releases more to balance, organics consume, CYA releases, etc.

This is why you continually top off the chlorine during the SLAM…to replenish the consumed chlorine and keep enough in reserves.

This is the general misunderstanding across pool owners and the industry. The recommended 1-4ppm of chlorine in a pool is assuming 0 CYA.
 
proavia said:
That's because none of the other sources understand the FC/CYA relationship or take the CYA level into account.
And those sources are stuck in the 1980's 'science'. TFP uses current science and backs it up with thousands and thousands of TFP members who follow the TFP methodology successfully.
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I understand that when it comes to calculating the chlorine target, but how much does the CYA make a difference when deciding the max chlorine level that is safe for swimming? a CYA level of 70 wouldn't like triple the safe limits, would it?
 
Mayday said:
I understand that when it comes to calculating the chlorine target, but how much does the CYA make a difference when deciding the max chlorine level that is safe for swimming? a CYA level of 70 wouldn't like triple the safe limits, would it?
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Please read CYA Chlorine Relationship - Further Reading

The safety of high chlorine levels when bound to CYA is explained in Aqua Magazine: CYA and Chlorine in Plain Language

CYA separates the chlorine into "Active Chlorine" which is a small safe amount and "Reserve Chlorine" which is bound to the CYA.
 

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casiokid said:
The amount of “active” chlorine in a pool with 70 CYA is not the full 28ppm you’re imagining. The chlorine is being chemically held by the CYA and only being released as the free chlorine gets consumed by the organic material or algae in the water.

I’m sure the other experts will give you the exact, mathematical proportions, but 28ppm chlorine at 70 CYA is the equivalent of a much smaller amount of chlorine with 0 CYA.

The difference is, with lower chlorine levels in a pool with 0 CYA, the organics will consume that chlorine quickly and there won’t be any more left to continue fighting, hence continued algae.

But with higher levels of chlorine in the water at 70 CYA, the organics consume the chlorine, CYA releases more to balance, organics consume, CYA releases, etc.

This is why you continually top off the chlorine during the SLAM…to replenish the consumed chlorine and keep enough in reserves.

This is the general misunderstanding across pool owners and the industry. The recommended 1-4ppm of chlorine in a pool is assuming 0 CYA.
Click to expand...
Does that mean a CYA level at 70 and chlorine at 28 PPM has the same chlorine effect of 10 PPM at very low CYA, like 20?
 
Mayday said:
Does that mean a CYA level at 70 and chlorine at 28 PPM has the same chlorine effect of 10 PPM at very low CYA, like 20?
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28 ppm of FC with CYA 70 has "Active Chlorine HOCL" of less then 1 ppm.

HOCl.gif
 
I have the Taylor 2006 test with the powder. I need to do a mustard algae slam, because they keep accumulating at the bottom of the pool. I will need to do a regular SLAM, then raise it to even higher levels (35ppm for 60 CYA). My question is, how am I supposed to test for FC levels at those high levels? Am I supposed to really do 70 drops of the reagent at 0.5 ppm per drop multiple times a day since I need to maintain that level for a few days, if not more? Or is there a different method for these high levels?
 
I am trying to get rid of Mustard Algae that collects at the bottom of my pool and steps. I generally maintain high FC levels, but there was a period at the start of the summer when we were away and the chlorine levels dipped down to nothing. Maybe algae started to form then and didn't die when I brought it to regular levels.

I am wondering why the recommendation for getting rid of the algae starts with a regular slam, then moves to higher FC levels. Why not start at the high FC level and maintain that until overnight tests are good?
 
I think there are high range dedicated chlorine tests out there, but I suppose I would invest in a speed stir to make SLAM testing easier if using the Taylor reagents.
 
I have mustard algae that collects on my surfaces and I am about to start a SLAM process to fight it. My cartridge filter is about 3 years old, and I have not treated it well. For example, I have used my electric pressure washer to clean it a few times (even if at low setting with wide nozzle) and maybe that damaged the surfaces, allowing poor filtration. I am planning of replacing it.

My question is, should I replace it before I do my SLAMs and fight against the algae (so it helps with the filtration), or should I replace it after the process is done (so that the new filter is clean and doesn't have algae stuck in it)?

Thanks.
 
When doing a FC test (or any other I guess) you are supposed to swirl the tube after every drop. With the fas-dpd test, when my FC is around 8, which corresponds to 16 drops, I put in the first 10 drops one after another before swirling. I hadn't considered what effect this may have- is batch adding the drops screwing with the results, or is that fine? Do you all stir diligently after every drop?
 
I don’t think so but I’m not a 100% on that. There is a bunch of people who’ll know for sure. I’ve been using a speedstir for years so I’m stirring throughout the entire process. I highly recommend a speedstir, once you use one you’ll wonder how you ever got by without it.
 

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