potassium monopersulfate

unix_1

New member
Jun 23, 2020
4
San Francisco, CA
OK, before I get blasted by the Leslie's Pool comments, let me start by saying lesson learned and flames accepted.

I recently restarted my pool after having it completely stripped down and replastered, replumbed, etc etc. After the first week, I noticed that the combined chlorine (CC) values were high while the free chlorine (FC) values were nearly undetectable. I was going to shock the pool and was convinced that I should use a product "Leslies Fresh and Clear". I had never used this before and was told that because my CC values were so high, the Fresh and Clear would not introduce additional chlorine into the pool but, because it was an oxidizer, it would release the combined chlorine. WRONG

I did a great deal of reading after dosing the pool with the monopersulfate (MSP) and realizing that the CC values had actually increased and my ORP probe was reading very high also. Found a great article from Taylor talking about "Shock Interference" and the fact the MSP would interfere with DPT CC readings unless an MSP neutralizing reagent was used in the test. Good for the DPT test, not the ORP readings. The Leslies employees did not know that MSP would interfere with the test and they dont stock the MSP neutraizing agent.

So my question is, does anyone know how long it takes for the MSP to be eliminated from the water naturally or is there something that I must use to neutralize it?

Thanks in advance.

-John
(I know, I know)
 
Last edited:

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,976
Franklin, NC
Matt or James may know the answer to the question. As you have figured out, MPS interferes with the CC test and reads a false high.

@JoyfulNoise @JamesW

Now, the bigger question. Do you have or have you orderd a test kit so you can take control of the pool?
 

unix_1

New member
Jun 23, 2020
4
San Francisco, CA
Matt or James may know the answer to the question. As you have figured out, MPS interferes with the CC test and reads a false high.

@JoyfulNoise @JamesW

Now, the bigger question. Do you have or have you orderd a test kit so you can take control of the pool?

I've got more test kits than I have pools :) water is mostly balanced on all fronts except CC which I can't correctly read until I get the neutralizer.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,062
Tucson, AZ
How much MPS did you add?

It should oxidize "stuff" fairly quickly and then it will get reduced to sulfates. 24-48 hours with lots of sun on the pool should be more than enough. You only need the "MPS Interference" kit if you were planning to use it on a regular basis as might happen with a hot tub or if you were trying to run a pool using one of those goofy mineral/ion systems (highly NOT recommended!).

You don't need "lots of test kits", you need ONE working test kit. Get either a K-2006 from Taylor OR a TF-100 from TFTestKits.net and then throw out all the others you have that are not Taylor-based reagents. Then you can test your own water yourself, post test results and the folks here will be happy to help you.
 
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unix_1

New member
Jun 23, 2020
4
San Francisco, CA
How much MPS did you add?

It should oxidize "stuff" fairly quickly and then it will get reduced to sulfates. 24-48 hours with lots of sun on the pool should be more than enough. You only need the "MPS Interference" kit if you were planning to use it on a regular basis as might happen with a hot tub or if you were trying to run a pool using one of those goofy mineral/ion systems (highly NOT recommended!).

You don't need "lots of test kits", you need ONE working test kit. Get either a K-2006 from Taylor OR a TF-100 from TFTestKits.net and then throw out all the others you have that are not Taylor-based reagents. Then you can test your own water yourself, post test results and the folks here will be happy to help you.

Thanks Matt. This is the information I needed.

Used just 2.5lbs and took the rest back to Leslies. I wont be using it because it simply messes with the ORP sensor on the controller. Will just use a chlorine based shock going forward.

As for my multipule test kits, they are all Taylor and given to me for a variety of reasons.... Taylor is all I have ever used.