To use, or not to use, Potassium Monopersulfate (MPS)?

saml

0
Jun 3, 2008
51
Near Knoxville TN
Hi all,

I have really been enlightened by the various discussions and first hand information available on this site, especially the Chlorine/CYA Chart by Chemgeek. That was an eye opener. I've been doing pretty well at finding information on most of my issues which I have been fighting a loosing battle with since we built a pool 15 years ago. A few years ago I had to replace the liner and it was a toss up to replace it or dig it up and fill in the hole. None the less, I still have a pool. This year was the worst yet and after reviewing a few articles I realized my high CYA (~180) seemed to be the first priority. I attribute this to nobody at the pool stores warning you about stabilized tablets coupled with the stabilized shock which I had been using for the past few years. My PH stayed low (~6.8) and the TA stayed high (~180) no matter what I threw at it. This year the water clouded up and and would not go away. After a gallon and a half of MA followed by a 50% drain and refill I'm somewhere bewtween 50-100 CYA, PH is between 7.2-7.8 with TA 80-120 and CH is about 250 and best of all I can see the bottom of the pool. I've taken up the BBB method and have been buying up Wal-Mart bleach and 20 Mule Team borax but with my TA level no baking soda yet. However, before the season started I bought up "several" 1# bags of potassium monopersulfate because last year I got in one of those "keep shocking till the level drops" and that was not pretty. I figured the MPS would help but now I read about how the stuff can mess up testing. I've used a few bags back a couple of weeks ago and was wondering [1] How long does it hang around? [2] Should I use it? and just to keep with the [3]point sermon rules, [3] Should I be using an algeacide, and if so what kind?

I'm open for any other words of advice, suggested articles, and words of encouragement.

Thanks
 
No, I read when I was sold that "type of shock" it is actually for shocking indoor pools....

Just use liquid chlorine a.k.a. clorox bleach.

If you haven't read Pool School
http://www.troublefreepool.com/pool-school/

Please do and then if you have further questions, feel free to post them.

Don't worry, I know it's alot of information to take in and it can be very overwhelming.

But quite honestly is going to be fine, just be patient and keep at it consistently all will be well.

If I can do it anyone can.

Look, the fact that you already dropped your CYA is a huge obstacle, and I would say 60% of your troubles are behind you, if not more.

No worries, mkay?
 
I don't think that the KMPS will really screw anything up for you. However, just use bleach. I use KMPS sometimes in the spa to verify presence of a bromine bank (bleach cannot do that), but in an outdoor pool, bleach is best for shocking.

I wouldn't worry about it though.

I don't think you need an algaecide. If anything, use polyquat, but it's usually not necessary if you keep sanitizer levels up.
 
MPS will read as CC unless you have the special reagent to neutralize it. As long as you are aware of that it usually isn't a problem. It can sometimes hang around in the water for a couple of days, rarely longer. There is little need for it in an outdoor pool, it is more expensive than the alternatives for outdoor pools, but you could use it the next time you have a high CC level if you want to.
 
MPS served a special need for me. I had an ammonia problem so besides having to bring down my ammonia level i also had 2-3 PPM CC. This would require 30PPM FC in addition to the 150+ PPM FC needed to defeat the ammonia. If you don't put in enough bleach you create more CC potentially making the problem even tougher to defeat. MPS has one ability that makes it useful in this situation - you can add it peacemeal a little at a time until your problem is neutralized. MPS will consume CC but will for 3-4 days make your CC level look HUGELY high. Using it I was able to gently (read without wasting money) reduce my CC to 0 (which was also a good indicator that I was killing off the ammonia problem). Also if you have a high CYA you may have to use an excessive amount of bleach just to shock but with MPS you can use the standard 1 bag per 10,000 gallons. I'd love to hear what someone more knowledgeable has to say about my theories :p MPS specifically doesn't oxidize algae very well - but if you don't have algae - like me - it seems it's a good fit. I use 2 bags once per week and half gal 6% bleach before swimming each time because my pool still won't hold FC (for long). Nobody can explain that one. i don't care. The water is clear and I'm not getting sick.
 
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