Dichlor Product Percentages

[dm8711]

This may have been explained previously, but in my searching forums I could not find this exact question answered. I have had my Hot Tub for quite some time. After use I have been putting a 35mm film canister (about 3/4 oz) of Multi Shock in it. This has been working great. The water stays nice and clear. Once in awhile I will super-chlorinate by putting a couple of them in. Then Baking Soda or Spa Down as needed.

The price on this shock is now over $5.00 a pound. (24 lbs is around $120 - it used to be $75 for a 25# pail of it.)

The Multi shock ingredients are SODIUM DICHLORO-S-TRIAZINETRIONE 58.2% with OTHER INGREDIENTS listed as 41.8%. Available Chlorine is 58% (Treat and swim as soon as 15 minutes.)

I now have found a product at my local Sam's Club which is HALF the cost. It is a box of 24 one pound bags for $57.34 !

BUT, the percentages and ingredients are drastically different.

Sam's "Quick Dissolving" shock ingredients are SODIUM DICHLORO-S-TRIAZINETRIONE "HYDRATED" 99% with OTHER INGREDIENTS listed at 1%. Available Chlorine is 55.5% (NO mention of being able to swim as soon as 15 minutes on this product)

My question is : What is going to change for me if I choose this new product ?

I don't understand the added word "Hydrated", or less "Other Ingredients", but I do see the available Chlorine is still pretty even.

Thanks for any help I can get on this. (I'm a newbie here at the forum)

[quantumchromodynamics]

You really don't want to use that much dichlor in your hot tub. Every ounce of dichlor in 375 gallons will raise the cyanuric acid level by about 10 ppm. You shouldn't be exceeding 40 ppm of cyanuric acid.

http://www.poolspaforum.com/forum/index.php?showtopic=13634

http://www.poolspaforum.com/forum/index.php?showtopic=23090

The dichlor from Sam's Club is the common form of dichlor and will work fine.

Is the product that you have "Omni Crystal Clear Multi-Shock"?

That looks like a blend of dichlor and other products. If the concentration of dichlor is 58.2 %, then I don't see how they get an available chlorine of 58 %.

The Multi-Shock is probably a rebranded version of DuPont's Multifunctional shock, which is a blend of Oxone (MPS) and dichlor. Since Available Chlorine is reported in units of chlorine gas equivalents, perhaps they are including the oxidizing capacity of the Oxone MPS as part of the "Available Chlorine".

Reference

MSDS

[dm8711]

First of all let me apologize for an error. The Multi Shock I have now DOES NOT list available chlorine at 58.2%. It doesn't list it at all ! You were correct that it couldn't be 58.2 (Sorry about that...it was late!)

Thanks for your quick response! So let me get this straight......I shouldn't be using just Dichlor to sanitize my tub ?

When I bought the tub 10 years ago the spa place that sold it to me gave me a bag of GUARDEX Multi Shock, some algaecide, up, and down, some test strips,and said this is all I would ever need to keep my tub fresh. He said that the Multi Shock was a NON CHLORINE substitute.

I have always just used GUARDEX or OMNI with 58% Dichlor in the tub. I have never used any straight Chlorine at all. I have always noticed in motel pools that the chlorine has a horrible odor and dries my skin badly so I was very happy not to use it in my own spa. (I realize some over chlorinate)

I went back to my dealer to get more of the Guardex (a long time ago) and told him about my "film canister" method of shocking my tub and he thought it was a great idea. I have never experienced any problems at all and the water is always nice and clear. We use our tub almost daily for anywhere from 15 minutes to more than an hour. We keep it at around 101 in the summer and 103 in the Northern Michigan winter.

We have City water which is not hard and very well balanced. We refill every 3 months. Only test every couple weeks. Very seldom do my test strips show the tub very far out of balance at all. (More times low than high) A little baking soda and good to go again. I clean the filter every week and a half. Filters last me a year or more without any great loss of suction.

I read your posts and see that the Spa place probably wasn't exactly correct ?

I thought the Dichlor was the answer to all my prayers because it made taking care of the spa seem so simple, and the tub was always clean. I can't stand the thought of straight bleach in the water as much as we use the tub.

What is all the extra Cya going to do to me ?

By the way in answer to your qestion, the pail I have now is GUARDEX CRYSTAL CLEAR MULTI SHOCK 58.2% which of course is the same as the OMNI you mentioned. So then would the amount of available chlorine probably be closer to 25% ? So is the stuff I just bought actually double the strength of the Guardex ?

Arrrggggggh.......Until today I was not confused (about this topic anyway)!

Thanks for your help.

[PaulR]

For hot tub water management I highly recommend Nitro's Approach to Water Maintenance. You start out using dichlor to build up around 30ppm CYA, then switch to bleach. I've been using that method for over a year and I love it.

What's the issue with bleach? It's sodium hypochlorite, it basically adds nothing but chlorine to the water. Using just dichlor, you will build up too much CYA, then you will need ever higher FC levels to get proper sanitation. Eventually you can't keep up, the water goes south, and you dump and refill it. Using bleach, the water will last longer.

You can add bleach after your soak, if it really gives you the willies. chem geek's rule of thumb is 5 oz 6% bleach per person-hour of soaking, IIRC.

--paulr

[gman]

quantumchromodynamics will explain the chemistry better than I....nevertheless...here's a simple layman's explanation.

Dichlor contains cyanuric acid (CYA), which is a buffer and controls the release of free chlorine, so the free chlorine is not dissipated too rapidly. Free chlorine combines with any contaminants in the water to neutralize them. The free chlorine is used up in the process (and becomes combined chlorine). To replace the depleted free chlorine, you add dichlor. Unlike the free chlorine, CYA is not depleted and remains in the water. However, every time you add dichlor, you are also adding more CYA. The more CYA you have, the more free chlorine you need to penetrate the CYA buffer.

Imagine a football game.... the offensive line is the CYA, the offensive quarterback is the contaminants, and the defensive line the free chlorine. All things being equal, some of the defensive lineman and linebackers will penetrate the offensive line and sack the quarterback. However, if after every "down" additional offensive lineman were added to the offense (CYA), but the number on defensive players remained the same (level of active chlorine), it would continually get harder and harder for the defense (chlorine) to reach the quarterback (contaminants).

Like you, I have a friend who had been following the dealer's recommendation and regularly used dichlor to sanitize her tub. She used test strips the dealer provided to test her water. She thought she was doing everything she should to keep her tub safe. Nevertheless, she eventually had issues with sanitation. When I tested her water with a proper drop test kit, her CYA levels were over 250 ppm. At that level of CYA, the standard level of free chlorine she was regularly adding was insufficient to be effective. And with each addition of chemicals, she was continuing to add more buffer.

As quantumchromodynamics stated, your CYA level shouldn't be higher than 40 ppm. The recommended level for hot tubs seems to be between 20 - 30 ppm. I keep my CYA at about 28 ppm. Once the CYA reaches around 30 ppm, you should be adding just plain chlorine bleach (See Nitro's Dichlor/Bleach method...available on this forum). Plain chlorine bleach does not contain CYA like dichlor. Unless you have some particular sensitivity to chlorine, you should not have issues by using just plain bleach unless the level of free chlorine you maintain in your tub is higher than recommended. (There are other posts on this forum that explain the different water chemistry requirements for pools versus hot tubs.)

I hope this helps a little.

To all the chemists out there, please forgive my poor analogy and my bastardization of the science of chemistry. No disrespect intended.

gman

[quantumchromodynamics]

Check the two references I put in my first reply to see two good write-ups about water chemistry.

Nitro's Approach To Water Maintenance

Dichlor/bleach Method In A Nutshell

The multi-shock contains dichlor and MPS. You can buy MPS as a separate product as use that to shock if you want to, but it is usually not needed as long as you keep you chemistry right.

[quantumchromodynamics]

I have never used any straight Chlorine at all. I have always noticed in motel pools that the chlorine has a horrible odor and dries my skin badly so I was very happy not to use it in my own spa. (I realize some over chlorinate)

The "chlorine smell" is not from over-chlorination. "Chlorine smell" is from Combined Chlorine. Combined chlorine is chlorine that has combined with organic contaminants, such as urine.

Shocking with chlorine or MPS will eliminate combined chlorine (aka chloramines) and restore the water to being fresh and clean. See the link in my signature for the recommended test kit the K-2006. With it, you can test for Free and Combined Chlorine.

Here is a page of interesting demo videos that show how to use the K-2006.

Scroll down the page and click on the video titled "How to Test (Free and Combined) Chlorine using FAS-DPD [updated 3/5/10]"

http://www.taylortechnologies.com/products_kitinfo.asp?&MarketID=1&KitID=2230

[dm8711]

Thanks guys for all your help on this topic. I learned a lot that's for sure. The links to the "How to's" are great too.

Oh, by the way QUANUMCHROMODYNAMICS.......you'll forgive me if I don't mention the "Motel Pool Urine thing" to my wife won't you ?

I see a K-2006 in my immediate future !

Thanks !

[quantumchromodynamics]

http://www.tftestkits.net/ has a good reputation for fast shipping and good service. Their TF-100 is an equivalent to the K-2006.

http://www.amatoind.com/taylor-k2006-test-p-555.html has a good price on the k-2006.