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Author Topic: Another chemistry question, this time MPS  (Read 2254 times)

michiganwinter

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Another chemistry question, this time MPS
« on: April 04, 2009, 04:54:35 pm »
Hi all,

First off I want to thank all of you for the advice regarding baking soda, my tub finally is balanced as far as PH and ALK!!!! Thanks again!

Now my next issue is MPS which is reading at next to zero. Isn't this shock? I do the weekly shock and then boosters every other day in between, and also boost with chlorine. What do I need to do to get the MPS level up? Is it super-shocking or am I missing something (not the first time)?

Thanks in advance for the good info I know is on it's way  ;)

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Another chemistry question, this time MPS
« on: April 04, 2009, 04:54:35 pm »

Jacuzzi Jim

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Re: Another chemistry question, this time MPS
« Reply #1 on: April 04, 2009, 05:17:35 pm »
 In my opinion you don't need to keep the level of shock up, it does its job then goes away.  Just keep your ph/alk in check, sanitizer here and there and call it good!   I only shock once a week, if that.

 Try not to micro manage to much, relax enjoy the spa!

Vinny

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Re: Another chemistry question, this time MPS
« Reply #2 on: April 04, 2009, 09:33:56 pm »
What Jim said.

If you're using chlorine it is important to not go too long without chlorine. I will put chlorine in every couple of days when I don't use the tub. If you're using bromine then MPS will reactivate the bromine.

As far as "shock" that can be accomplished 2 ways - use MPS at the recommended dose and it will burn off the combined chlorine in the water or use chlorine at the dose of 10x the combined chlorine reading to burn off the combined chlorine in the water. I find MPS does a great job at burning off the gunk that causes foam as long as you get most of it out by scooping it out.

chem geek

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Re: Another chemistry question, this time MPS
« Reply #3 on: April 05, 2009, 03:36:59 am »
MPS is a decent oxidizer, but it doesn't stick around very long, not usually more than a day.  The decomposition rate of MPS at spa temperatures is about 12% per hour so is 90% decomposed after 18 hours (95% decomposed after 24 hours).  Chlorine can last quite a bit longer, dropping about 25% per day when the tub is not in use (if you have an ozonator or are have accumulated stuff to oxidize in the spa, then the chlorine drop can be 50% or more per day).

Bather waste from sweat and urine will consume a lot of oxidizer.  At hot spa temperatures (100F-104F), one person-hour of soaking takes around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of MPS to oxidize this bather waste.  Many people simply do not use enough oxidizer in their spa.  The typical 2 teaspoons of Dichlor is good for one person soaking around 30 minutes or two people for 15 minutes.

So if you are going to be using primarily MPS (only if you have Nature2 or another silver ion system), then you will need to add it every day if you are using the tub that frequently.  If you are using primarily chlorine, then you can go a few days without adding chlorine if you aren't using the tub (as Vinny says, you don't want to go too long before you add chlorine) but whenever you use the tub you'll need to add chlorine either before or after each use (depending on whether you want to soak in higher chlorine levels or not).

Richard
« Last Edit: April 05, 2009, 03:40:27 am by chem_geek »

michiganwinter

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Re: Another chemistry question, this time MPS
« Reply #4 on: April 05, 2009, 08:42:44 am »
Thanks folks! It looks like it is probably not enough MPS and chlorine then since I use the tub 2-3 times daily most days (incredible high blood pressure relief, way better than the pills) and just boost once a day. Looks like time to do more than boost and weekly shock.

You guys are a great help, thanks so much!

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Re: Another chemistry question, this time MPS
« Reply #4 on: April 05, 2009, 08:42:44 am »

 

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