Hot Tub Forum
Original => Hot Tub Forum => Topic started by: devilwoman on April 08, 2006, 06:48:20 pm
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Just wondering (as I read over Vermonters Style dosing) if you are dosing per your tubs chlorine demand, reaching between 2-3ppm and it is killing all the nasty germs and such after each time you soak...why do you need to Shock? Sorry if this is such a basic question...
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you get an accumulation of combined chlorine over the week and the shock gasses it off.
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There's also the reason of adding a superchlorination if you use chlorine to shock. This gives you the benefit that if the original dose didn't kill everything growing the extra chlorine will do it.
Just remember for the chlorine to get rid of the combined chlorine the free chlorine needs to be 10x the combined amount. Typically I will use MPS if my reading is over 0.5 PPM, I will add 3 PPM chlorine to the tub 20 min after adding the MPS.
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Vinny why do you use both to Shock?
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If the combined chlorine (CC) is too high I then would need a lot of chlorine and if I want to soak I would soak in what ever level of chlorine. Anything under 0.5 PPM of CC gets hit with 6 PPM of chlorine. Another reason I use chlorine after MPS is I don't want to shock and not have chlorine in the tub any length of time (2+ days).
Enhanced shock contains chlorine and so I figured I could do the same.
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I do it a little differently. Because I use a minimal amount of dichlor after use, I like to get my free chlorine level to the 3-5 ppm level once per week. This would be about 1 tablespn dichlor for my 485 gallons of water. I shock with 2 tablespns unbuffered MPS when needed.
Used or spent chlorine form chlorimines. This is what gives a chlorine spa or pool that "chlorine smell". This is measured by the difference between total chlorine and free chlorine and is called combined chlorine. Combined chlorine has very little value. When the combined chlorine level reaches .2 ppm, you must shock to oxidize or vaporize to purge them from your water. This can be done by quickly raising the free chlorine level to what is called breakpoint chlorination or by adding a sufficient amount of non chlorine shock. There are advantages and disadvantages to both. Shocking with chlorine will add to CYA levels and you cannot use the spa until the chlorine level drops, but you get the benefit of a superchlorination. Non chlorine shock has the advantage of use almost immediately after shocking, but will add to TDS. It is also more foolproof because if you don't add enough, it still oxidizes what it can..if you add too much, it stays until it can ozidize. With chlorine shock, if you don't add enough, shocking will not occur and you will have water with a high chlorine level and still have chlorimines. After shocking, your free chlorine levels should equal your total chlorine level.
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Tony how long after shocking should both levels be the same?
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I do it a little differently. Because I use a minimal amount of dichlor after use, I like to get my free chlorine level to the 3-5 ppm level once per week. This would be about 1 tablespn dichlor for my 485 gallons of water. I shock with 2 tablespns unbuffered MPS when needed.
By the phrase "when needed" do you mean when you want to soak right away? Other wise when do you know when to use MPS or Dichlor for shocking?
Used or spent chlorine form chlorimines. This is what gives a chlorine spa or pool that "chlorine smell". This is measured by the difference between total chlorine and free chlorine and is called combined chlorine. Combined chlorine has very little value. When the combined chlorine level reaches .2 ppm, you must shock to oxidize or vaporize to purge them from your water. This can be done by quickly raising the free chlorine level to what is called breakpoint chlorination or by adding a sufficient amount of non chlorine shock. There are advantages and disadvantages to both. Shocking with chlorine will add to CYA levels and you cannot use the spa until the chlorine level drops, but you get the benefit of a superchlorination. Non chlorine shock has the advantage of use almost immediately after shocking, but will add to TDS. It is also more foolproof because if you don't add enough, it still oxidizes what it can..if you add too much, it stays until it can ozidize. With chlorine shock, if you don't add enough, shocking will not occur and you will have water with a high chlorine level and still have chlorimines. After shocking, your free chlorine levels should equal your total chlorine level.
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After shocking, leave your cover off for about twenty minutes to allow gasses to dissipate. After that the shock process is complete and you should have no combined chlorine. To be practical, the next day is a good test if you are concerned.
"When needed" for me is when the combined chlorine level is .2 ppm. Depending on use, this could be one week or two weeks as a general rule. Now, .2 ppm is a very small value to determine. I use a Taylor test kit. I wait until my free chlorine level is zero. With the Taylor kit you test for free chlorine first and add drops to test for total chlorine. Zero gives no color. If my total chlorine also tests zero (no color), I know I am fine. If I get any pink, its time to shock. I check this weekly along with pH. I check TA monthly.
Hope this all makes sense.
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Shocking is indeed needed to eliminate chloramines, but that is only valid in a situation using dichlor as your sanitizer.
Whether you use dichlor, bromine, or biguinide systems you need to shock.
If your using chlorine or MPS based shock for dichlor or bromine system, or peroxide for biguinide systems. The primary reason is to eliminate nitrogen based compounds from your tub (sweat, urine, body oils, etc.)
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'it's all still a mystery to me.
When I shock with a high dosage of chlorine to to oxidize the chloramines, it sounds to me as if I'm just creating new chloramines? ???
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'it's all still a mystery to me.
When I shock with a high dosage of chlorine to to oxidize the chloramines, it sounds to me as if I'm just creating new chloramines? ???
Not without something to create them. Chloraminies are formed by the reaction of free chlorine with ammonia wastes from bathers. Shocking with chorine raises the chlorine level dramatically in a short period of time. When free chlorine measures ten time the combined chlorine level, breakpoint chlorination occiurs. Chloramines are oxidized (explode) and are released as a gas (why you keep your cover off). Its all just chemistry.
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Not without something to create them. Chloraminies are formed by the reaction of free chlorine with ammonia wastes from bathers. Shocking with chorine raises the chlorine level dramatically in a short period of time. When free chlorine measures ten time the combined chlorine level, breakpoint chlorination occiurs. Chloramines are oxidized (explode) and are released as a gas (why you keep your cover off). Its all just chemistry.
AHA! That explanation did it for me. Thanks.
:)
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How long should the cover be off?
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I generally leave the cover off 20 minutes when using 6 PPM for shocking and 1 hour if I hit it harder with more chlorine. I'm not that stick with this rule at times but if I have the time (weekends) I try to stick with this.
Regular chlorination, 3 PPM, gets about 5 min or less.
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Great information thanks!!!
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I generally leave the cover off 20 minutes when using 6 PPM for shocking and 1 hour if I hit it harder with more chlorine. I'm not that stick with this rule at times but if I have the time (weekends) I try to stick with this.
Regular chlorination, 3 PPM, gets about 5 min or less.
How do you know how much chlorine gives you 6 PPM and 3 PPM?
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I would think it depends on your water and how much the tub holds. If I recall correctly, 2 TBSP of dichlor in MY tub (500 gallon) gets to about 10ppm, that's with a fresh fill.....so I figured 1 TBSP is 5ppm, etc....You could test your own, see what you come up with.....
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How do you know how much chlorine gives you 6 PPM and 3 PPM?
By testing the water 10 minutes after adding the chlorine.
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Hmmm....and then there's that.... *lol* what drewstar said.
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Are the Leisure Time test strips an OK way to test these levels?
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Are the Leisure Time test strips an OK way to test these levels?
That's what I use and have had no problems.
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Vinny,
My normal dichlor dose is 1 teaspoon after I get out of the water. When I shocked I use 3 tablespoons of dichlor. Too much I know my calculations were off because...well it's a long story...but mostly because I'm stupid. Should the free chlorine level be close to 0 the next day say 24 hrs later or will it be longer before it comes to 0. I realize now why people use MPS to shock so you can use the tub sooner. The water smelled ok, but the reading was definately over 5ppm 12 hours later.
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Vinny,
My normal dichlor dose is 1 teaspoon after I get out of the water. When I shocked I use 3 tablespoons of dichlor. Too much I know my calculations were off because...well it's a long story...but mostly because I'm stupid. Should the free chlorine level be close to 0 the next day say 24 hrs later or will it be longer before it comes to 0. I realize now why people use MPS to shock so you can use the tub sooner. The water smelled ok, but the reading was definately over 5ppm 12 hours later.
It could be longer than 24 hours but it's OK to soak in chlorine. With everything that's said here if you read "the manual" we're supposed to put chlorine in before not after. But thinking logically IF we soak with close to 0 chlorine and put in a dose we're still killing the nasties. The only problem is if someone gets in the tub with really bad nasties there's nothing to kill it while you're in the tub.
In my tub I use about 1 - 2 teaspoons after soaking, this gives me 1.5 - 3 PPM chlorine. My tub is 400 gallons so your tub would yield a little less readings than mine.
Too much chlorine is not bad and actually is probably good since if something was to be growing, that much will definately knock it out unless it grew to a biofilm mass then it wouldn't do too much. Regular chlorination and keeping water flowing to all parts of the tub will stop anything from getting to that level.
As far as soaking in "high" levels of chlorine ... MY tub on the last water change developed chlorine lock. My chlorine would stay for days with what ever amount of chlorine I put in. I had thought that the problem went away and I shocked the tub, soaked in it, added chlorine .... well by the end of the week I got in and smelled chlorine and thought it was combined chlorine. I took out my test kit and found it was WAY HIGH chlorine. It was over 20 PPM, my tub still had the problem but I wasn't aware of it. If you do soak in chlorine, even at 6 PPM I don't believe it'll hurt you (may kill the suit though - no ill effects on mine).
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Vinny and Tony or anyone who cares,
Do you have a Taylor Pool & Spa Water Chemistry book? If so, turn to page 31. Under the section "Disadvantages to MPS" it says "Unlike breakpoint chlorination, will not remove combined chloramines".
This seems strange to me. Is this correct? When I shock with MPS I can't seem to completely eliminate my combined chlorine like I can with dichlor. There's always a slight tint of purple when I test for combined chlorine using my Taylor Test Kit after shocking with MPS. Maybe it's just me.
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Gomboman, that you for asking that! I KNEW I saw that statement somewhere, and now I realize it was from the tayor book. I wondered about that too.
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I've read that myself and then read the label on a MPS bottle. It's contradictory in their terms according to the bottle.
I have an older Taylor booklet (2003) and it doesn't have that statement in it. My new one (2004) does. Maybe something was found out between the 2 publishings, maybe MPS doesn't work or maybe there is a misprint in the Taylor book.
I really don't use MPS that often to experiment in my tub with it. I tend to have very low combined chlorine and a large (6 PPM) dose takes care of breakpoint chlorination in my tub.
The problem I see with MPS is it leaves the kits with a false reading on combined chlorine, so it's impossible to really determine if you have any unless you stopped soaking, didn't add chlorine and tested your water with something every day for a week (?) to see if the combined chlorine goes away.
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Mine does not say that either.
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The problem I see with MPS is it leaves the kits with a false reading on combined chlorine, so it's impossible to really determine if you have any unless you stopped soaking, didn't add chlorine and tested your water with something every day for a week (?) to see if the combined chlorine goes away.
MPS interferes with chlorine reading? Just combined, not free? For how long after adding- a week? How is that possible, if some people shock with it weekly?
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MPS interferes with chlorine reading? Just combined, not free? For how long after adding- a week? How is that possible, if some people shock with it weekly?
It interferes with chlorine reading right after you add. Wait an couple of hours to test after adding. It is not an issue.
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Vinny and Tony or anyone who cares,
Do you have a Taylor Pool & Spa Water Chemistry book? If so, turn to page 31. Under the section "Disadvantages to MPS" it says "Unlike breakpoint chlorination, will not remove combined chloramines".
This seems strange to me. Is this correct?
NO! This is not correct! Any MPS that is added will eliminate as many chloramines as it can. Though breakpoint is occuring, it IS NOT an "all or nothing" reaction like with chlorine based shock.
MPS can give false total chlorine readings for up to [glb]72 hours[/glb]
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According to Dupont, the company that developed and manufactures MPS, chloramines are eliminated with use of the product. It is what the product is intended to do.
This link has much information regarding MPS.
http://www.dupont.com/oxone/faq.html