Using Active Oxygen as an irregular shock treatment

[Toby H4B]

Hello All TFP people, hoping you can help.
I manage and maintain 15+ pools in Spain for clients ranging from 5000L (yes I appreciate that's barely more than an oversized bathtub) to 100,000L and have an additional 3 more pools (including one shared by 6 apartments) coming on board for 2023 .

I'm really trying to understand whether Active Oxygen is a chemical worth adding to my arsenal for irregular shock treatments of the smaller pools (>50,000L).
I had a couple of instances last season where we had back-to-back guest arrivals. With such heavy usage in this particular property I tend to keep the FC around 2.5-3ppm, however CC reading was 0.4 so indicated need for shocking. Obviously I had no choice but to shock as normal and advise the guests they weren't able to swim until chlorine levels fell to at least 5ppm; could in an instance such as this Active Oxygen be used to do the shock treatment without the need to raise chlorine levels? This way the pool could be back being used quickly and I'd not have to see the teary eyed look of children desperate to jump in on a boiling hot day.
Any thoughts/advice greatly appreciated.

 

[Jimrahbe]

Toby,

Let's see if Matt has any input.. @JoyfulNoise

Active Oxygen "sounds" pretty scammy to me, but then again, I am not close to being a chemical expert.

Thanks,

Jim R.

 

[Mdragger88]

I have a feeling it’s MPS.
monopersulfate

MPS

A non chlorine oxidizer or ‘shock’. It is acidic and will cause lower pH and … Read more…

www.troublefreepool.com

What was the cya level of the pool?
FC/CYA Levels

Do you have specific guidelines you must follow legally that dictate 5ppm fc?

 

[PoolStored]

I found two EU products that are called "Active Oxygen"

potassium peroxymonosulfate
Pentapotassium bis(peroxymonosulphate) bis(sulphate)

Seems like MPS.

 

[JoyfulNoise]

Please post the name and manufacturer of the chemical you think you should add.

 

[Toby H4B]

Hi guys, so the manufacturer I was looking at is Bayrol who sell quality chemicals in Europe. As PoolStored correctly commented the chemical is peroxymonosulphate.
Mdragger88 not legally bound, but as this is a holiday rental property i have to er on the side of caution so I would always advise guests to wait until FC level was 5ppm or below. CYA at the time was 32.
I really wish we could get some of the products you guys get in the states, seems there are so many more comprehensive options

 

[JoyfulNoise]

You can certainly use MPS in a high bather load tub but you you have to realize that MPS and chlorine will neutralize one another to a certain extent. So you want to use MPS strategically - after a big bather load BUT BEFORE you add any chlorine, you can add the MPS to help breakdown the bather waste. Then, after 24 hours, you should add chlorine back. BUT, MPS will interfere with your FC/CC testing and can give you false high CC readings. Taylor in the USA sells an MPS interference removal reagent that lets you measure FC/CC accurately when MPS is potentially present. If you can’t get that in the EU, then you’re going to have to experiment because the MPS will cause testing problems. Also, MPS is acidic so you’ll also have to carefully monitor pH to make sure you’re not causing any problems with that.

Finally, long term use of MPS will add sulfates to the water. Sulfate build up can attack concrete surfaces and cause metal corrosion. There are no easy tests for sulfate levels and so you’ll need to be mindful of the build up of sulfates just like you need to be careful with the build up of CYA. MPS is ok in lost hot tubs because you are exchanging the water so frequently that the sulfates aren’t an issue. But, I’m a large volume swimming pool, water gets changed less frequently and build up becomes a problem.

 

[mgtfp]

Have a look at the FC/CYA Levels that Mdragger posted. 5ppm at CYA 30-40 is actually not that much.

For residential back yard pools, we follow this chart, that considers that most of the chlorine is in a chemical bond with CYA, where it still shows up as FC, but is no longer contributing as a sanitiser/ oxidiser, only a small fraction is available as HOCl. As an example, 12ppm FC @ 30ppm CYA has the same amounts of HOCl than 0.64ppm FC @ 0 CYA, and is absolutely safe to swim in.

Unfortunately, as a commercial pool service provider you might be bound to operate within the limits specified in your locally applicable legislation. And double unfortunately, what is written down as a "law" is not necessarily what is "right". It's just what has been written down by people familiar with law, who have been advised by lobbyists, who are not familiar with science (or are willing to ignore it under the right circumstances). If you are interested in understanding the science, there is lots to read here. On a more basic level in the Pool School articles and the TFP Wiki, or going deeper in the sticky threads at the top of The Deep End...

The FC limits commonly applied by the traditional pool industry don't consider the chemical equilibriums between chlorine and CYA, FC and CYA are treaded as being independent from each other. These limits consider FC 5 @ CYA 0 to be identical to FC 5 at CYA 40 in terms of chlorine "aggressiveness". But in fact, FC 5 @ CYA 0 has (at pH 7.5 and 25°C) the same HOCl concentration as roughly FC 35 @ CYA 40, or FC 70 @ CYA 80.

I am very happy to let my son swim in our pool with a CYA of 80ppm as long as the FC is not higher than 31ppm (which is the SLAM-FC for CYA 80). This would be equivalent to FC 0.64ppm without CYA. FC 5 at CYA 0 would certainly be declared out of bounds in our back yard pool.

Again, in your case you have to follow what ever is legally binding in your jurisdiction, which I can't assess.

 

[JoyfulNoise]

Have a look at the FC/CYA Levels that Mdragger posted. 5ppm at CYA 30-40 is actually not that much.

For residential back yard pools, we follow this chart, that considers that most of the chlorine is in a chemical bond with CYA, where it still shows up as FC, but is no longer contributing as a sanitiser/ oxidiser, only a small fraction is available as HOCl. As an example, 12ppm FC @ 30ppm CYA has the same amounts of HOCl than 0.64ppm FC @ 0 CYA, and is absolutely safe to swim in.

Unfortunately, as a commercial pool service provider you might be bound to operate within the limits specified in your locally applicable legislation. And double unfortunately, what is written down as a "law" is not necessarily what is "right". It's just what has been written down by people familiar with law, who have been advised by lobbyists, who are not familiar with science (or are willing to ignore it under the right circumstances). If you are interested in understanding the science, there is lots to read here. On a more basic level in the Pool School articles and the TFP Wiki, or going deeper in the sticky threads at the top of The Deep End...

The FC limits commonly applied by the traditional pool industry don't consider the chemical equilibriums between chlorine and CYA, FC and CYA are treaded as being independent from each other. These limits consider FC 5 @ CYA 0 to be identical to FC 5 at CYA 40 in terms of chlorine "aggressiveness". But in fact, FC 5 @ CYA 0 has (at pH 7.5 and 25°C) the same HOCl concentration as roughly FC 35 @ CYA 40, or FC 70 @ CYA 80.

I am very happy to let my son swim in our pool with a CYA of 80ppm as long as the FC is not higher than 31ppm (which is the SLAM-FC for CYA 80). This would be equivalent to FC 0.64ppm without CYA. FC 5 at CYA 0 would certainly be declared out of bounds in our back yard pool.

Again, in your case you have to follow what ever is legally binding in your jurisdiction, which I can't assess.

All excellent points. However, science and reasonableness rarely make much headway in a legal court. If I owned a rental/vacation unit that saw people from all over, I too would tell people not to get into the water body until the FC is below 5ppm. Not because I don’t believe in the science but because I believe in the litigiousness of human beings. All it takes is one cantankerous individual to find out that the FC was above what all the regulations say is “safe” and they start to blame every problem under the sun on you and your dangerous pool care beliefs spouted by a bunch of pajama-wearing keyboard warriors living in their mom’s basement. Itchy skin rash? Too much FC. Watery, red eyes? Too much FC. Hair loss? Too much FC. Wife left me for another man (or woman … let’s not be all judgy … )? Too much FC.

It’s a water-filled personal injury lawsuit waiting to happen …

 

[mgtfp]

All excellent points. However, science and reasonableness rarely make much headway in a legal court. If I owned a rental/vacation unit that saw people from all over, I too would tell people not to get into the water body until the FC is below 5ppm. Not because I don’t believe in the science but because I believe in the litigiousness of human beings. All it takes is one cantankerous individual to find out that the FC was above what all the regulations say is “safe” and they start to blame every problem under the sun on you and your dangerous pool care beliefs spouted by a bunch of pajama-wearing keyboard warriors living in their mom’s basement. Itchy skin rash? Too much FC. Watery, red eyes? Too much FC. Hair loss? Too much FC. Wife left me for another man (or woman … let’s not be all judgy … )? Too much FC.

It’s a water-filled personal injury lawsuit waiting to happen …

You are absolutely right (as usual...). Unfortunately, the law system's primary reason for its existence is to make rich people, who know how to play the game, richer.

Even though, the real reason for all of the above mentioned symptoms of high FC are more likely to be caused by low FC - unsanitary water and build up of CC due to not sufficient FC being available to complete the oxidation chain.

CC is something we don't really think about much because they don't really have a chance to accumulate in a TFP pool, particularly outdoors with natural UV. But when CCs build up, there is no CYA moderation. FC 0.5 with CYA is nothing, that's what we are used to. But FC 0.5 with no CYA is witches' brew (well, I'm exaggerating, it's actually pretty good, just under slam). But CC is always the same. You won't smell FC 10 at CYA 80. But you will always smell CC 1 - and attribute that to "high" chlorine. But in a sufficiently chlorinated back yard pool, those CCs would never have accumulated in the first place.

That all puts pool services into a real dilemma. For legal reasons they (have to) fear high FC. But the actual challenge is to ensure that FC doesn't get too low before turning up for the next visit in a week's time.

I guess, the best option would be turning all the pools one is responsible for into salt pools. Maybe in combination with a Waterguru?

 

[Toby H4B]

Wow guys I can't thank you all enough. In all my years doing pools and despite the hundreds of hours of reading various articles I'd never considered the FC/CYA relationship and how that impacts readings. I should add that 80% of my pools are salt water, which does add an extra layer of complication (albeit the chemical principals are the same).
Regarding Active Oxygen/MPS, this stuff is crazy expensive and if it's gonna throw my CC readings out and mess with my chemistry I'd rather leave it well alone.

 

[mgtfp]

I should add that 80% of my pools are salt water, which does add an extra layer of complication (albeit the chemical principals are the same).

Salt is great (at least if the salt is being recycled with a salt water chlorine generator into chlorine ).