Bleach/chlorine Recipe?

[shock]

I have been using Nature2 and have also encountered hot tub rash due to inadequte levels of sanitizer. After looking through this forum I have a few questions on the bleach/chlorine recipe.

What would the recipe be for a 325 gallon tub, with ozonater?

Here is what I have gathered from reading through other posts.

Balance water, 7.2-7.6 PH and 80-120 TA

use some stain/scale control when filling tub

Check calcium hardness and adjust to ~150ppm

After this is complete use Diclor initially maintaining 4ppm in the spa until you have added a total of 20ppm Free Chlorine cumulative. So if I read another post correctly 1/2 tablespoon of bleach raises 100 gallons 1ppm so to raise 325 gallons to 4ppm would be 6.5 Tablespoons of bleach, so half of that would acheive the same 4ppm in 325 gallons using Dichlor, which would be 3.25 Tablespoons of Diclor.

What I am getting at is to acheive a cummulative of 20ppm I would have to use 16.25 Tablespoons of Diclor and then after I have put this amount in the spa I then switch over to using bleach to maintain the 4ppm until I drain and refill the spa.

Does this sound right so far?

Once this is complete how often should I check the spa and or add bleach to the spa??

Do I need to check chlorine levels daily??

Can I get away with checking chlorine levels less often if I add a mineral stick such as Nature2 to the Spa?

As for Non-chlorine shock(MPS) do I add this on a weekly basis to shock?

Do I shock weekly with chlorine or MPS?

Do I need to do anything as in add MPS or chlorine to the spa upon entry or exit if I maintain the spa at 4ppm of chlorine?

Just trying to get a good idea of what is needed when I drain and refill my spa if I go to a bleach/chlorine only set-up!?!?

[Pathfinder]

if you are using dichlor you do not need bleach when you first fill your tub you will "shock" the water to kill any organics or bacteria in the water. which is usually about 26-30grams of dichlor after about 6 hours you should have residual chlorine reading this is where you will adjust if you have to add any dichlor at all most people using this method just add 1 tablespoon or teaspoon after they are done using. Then a shock once a week with your MPS to get rid of any organics in the water. Do not use bleach at all

[chem geek]

if you are using dichlor you do not need bleach when you first fill your tub you will "shock" the water to kill any organics or bacteria in the water. which is usually about 26-30grams of dichlor after about 6 hours you should have residual chlorine reading this is where you will adjust if you have to add any dichlor at all most people using this method just add 1 tablespoon or teaspoon after they are done using. Then a shock once a week with your MPS to get rid of any organics in the water. Do not use bleach at all

I disagree. If you don't switch to bleach after a cumulative dose of around 20 ppm FC of Dichlor, then additional Dichlor will continue to increase the level of Cyanuric Acid (CYA) and that increased level makes the chlorine less effective. At some point, typically after about 2 months, there is so much CYA in the water that the bacteria that causes hot tub itch will thrive. There were 3 or 4 cases of hot tub itch reported on this forum and every single one occurred after a couple of months of using only Dichlor (or Dichlor plus MPS shock).

Remember that for every 1 ppm FC you add with Dichlor, you are also adding 0.9 ppm CYA. Dichlor is chlorine attached to CYA (so is Trichlor, but that has more chlorine per CYA).

You will likely need to add chlorine daily, but you can just check chlorine levels daily for a while to see how quickly it goes down and how often you need to add it to try and maintain 4 ppm (so adding more to get to 8 ppm and then letting it drop to 4 ppm before adding again).

You add non-chlorine shock (potassium monopersulfate, KMPS) weekly.

You typically add your chlorine either some time (half-hour or an hour) before entry or right after exit. You should have the cover off for 5 minutes or so before entry to dissipate chlorine smell (if any).

[Pathfinder]

Why are you talking about stablizer levels in hot tubs especially when you are using small amounts of dichlor this isnt a pool completely different forms of use the only way anyone should be concerned about cya levels is if they are using pucks or granules in a stable form from pools or using trichlor which shouldnt be used.

Your name might be chem geek but you should really learn more than what you find in research and theory

Just because someone stated the got itchy from their tub doesnt mean its bc of cya there could have been many factors such as improper sanitation on the perimeter of the tub, lack of shocking,unbalanced water....

I have 10yrs of of relevant hot tub and pool chemistry experience and have given seminars at my stores.

Whats your experience in the industry???

[Dr. Spa]

uh oh. here comes trouble

[Pathfinder]

LOL

[waterbear]

LOL

Well, CYA is a concern in chlorine spas. Many state health departments have outlawed it's use (and dichlor use) in hot tubs because it can decrease chlorines effectiveness enought to allow pseudomonas to grow (this is what causes 'hot tub itch') along with some other nasties! For each 1 ppm FC that dichlor adds to the water it also add .9 ppm CYA. Given the small volume of water in a spa this can lead to very high CYA levels in a very short time of use! Trichlor that is used in pools actually adds LESS CYA to the water (.6 ppm CYA for each 1 ppm FC).

[shock]

Sounds great thanks for the help everyone.

chem geek thanks for info on the bleach system sounds like it makes sense, definitely worth a try as it is a cheap sorce of chlorine, and all ready a liquid making easy to add.

chem geek from your statement of 4 ppm of chlorine am I under the correct assumption that the spa should never go below 4ppm of chlorine?

By shocking once a week with MPS does this eliminate the need for a chlorine shock?

At what level is the tub safe to enter? ex. 10 ppm of chlorine and below??? Just wondering what kind of a window I have above 4ppm before you start seeing problems such as clothes fading etc.

If I am unable to attend to the tub for a week or more, is it a good idea to build up the chlorine level high before I leave, or just leave it and shock it when I get back.

Thanks for all the help

[chem geek]

Pathfinder,

The chemistry of Cyanuric Acid and Chlorine in water doesn't change just because it is in a hot tub. Dichlor and Trichlor are both Cyanuric Acid molecules that have some of their hydrogen replaced with chlorine. In the case of Trichlor, all 3 hydrogen are replaced with chlorine. In the case of Dichlor, 2 of the hydrogen are replaced with chlorine. See this link for a diagram showing Dichlor, this link for Trichlor, and this link for Cyanuric Acid. When in water, all of the trichlor and dichlor both produce chlorine and cyanuric acid as well as all the various combinations in equilibrium.

Did you read this post of mine which has links to those reporting hot tub itch (or hot tub lung) on this forum? I have also followed up with these people via PM'ing to see if this is working for them. The hot tub lung was diagnosed from a doctor so I really don't think people are making this stuff up or are just having allergies. Also, take a look at the links to the Department of Health in Pennsylvania and the links to technical posts I have made. I don't understand specifically what it is that you are questioning.

[chem geek]

shock,

To be conservative, the 4 ppm FC is a minimum, but I don't think it's terrible if it gets lower some of the time so long as it is at least that amount much of the time. Essentially IF the bacteria can reproduce faster at a lower chlorine level of, say, 2 ppm FC, then having it another time at 6 ppm FC should wipe out whatever reproduced earlier. There aren't studies showing this exact relationship. I calculated the 4 ppm FC with 20 ppm CYA based on what are known as CT (99.99% or 4-log) values of 30-50 which are studies of how much chlorine it takes for how long to kill the bacteria that causes hot tub itch. But those studies are at somewhat cooler temps.

Yes, using MPS once a week should eliminate the need for chlorine shock (so long as chlorine levels are consistently maintained). Just remember that MPS will measure as Combined Chlorine (CC) in the chlorine test though there is a reagent from Taylor that eliminates this interference. You shouldn't have to check for CCs if you use MPS regularly since there simply won't be any. The use of MPS is not only to oxidize organics, but also to virtually eliminate chlorine disinfection by-products which are more of a problem in a hot tub due to lack of sunlight breakdown and the higher temps and aeration volatility.

At 10 ppm FC and 20 ppm CYA, the disinfecting chlorine level is equivalent to 0.9 ppm FC with no CYA so it's really not very much. For comparison, the indoor pool that my wife uses typically has 2-4 ppm FC with no CYA and her swimsuits degrade (the rubber loses elasticity and the fabric becomes thin) but they don't usually fade (they are "chlorine-resistant" swimsuits). So there is no question that the higher chlorine is harder on swimsuits, but your 10 ppm should be from 2-4 times less strong than typical indoor pools. So, it's safe, but you'll probably notice some degradation over perhaps a year or two of use rather than the 5 months that my wife experiences.

If you know you will not be using the tub for a while, it is best to boost the chlorine rather than leave it. It's much easier to prevent problems or bacterial growth than it is to deal with it later. By the way, the MPS shock won't deal effectively with the bacteria. Only chlorine will do that. So if by chance you come back and find the FC very low or at 0, then shock with chlorine to kill any bacteria (10 ppm FC over 4 hours should be plenty).

[waterbear]

Pathfinder,

Chemgeek is, as usual, right on the money! He might not be in the industry but he had a great deal of knowledge and his information is accurate. I am in the industry and I agree with everything he has posted in this thread!.

[shock]

chem geek, thanks for all your help!!

This is great information and I look forward to using this method going forward!!

[shock]

After using bleach as a source of chlorine I have noticed it is hard to breath when in the tub. It makes you want to cough and get your head away from the water (hot tub is outside).

Just wondering if I am doing something incorectly or is this just a side affect of using a higher concentration of chlorine in the water??

[waterbear]

I would have to guess that you have combined chlorine in the water and need to shock wit chlorine. If the tub is outdoors I see no advantage to shocking with MPS. MPS will NOT break down combined chlorine. It works by oxidizing organics before they combine with the chlorine but only if a residual level of MPS is kept in the water by using it on a regular basis. If you could post a set of test results that would be helpful.

[shock]

OK, here are the test results,

FC=2ppm

CC=2.5ppm

PH=7.8

TA=80

CH=170ppm

CYA= not sure black dot did not disapear

Other info, water temp at 97 degrees during testing. Chlorine source is Chlorox regular bleach. Nature 2 cartridge still in spa. When the jets are on is when you notice the sense of not being able to breath near the water, when the jets are off there is no problem breathing the air near the water. There is also foaming in the water with the jets on which I have not had until recently. I have not used any MPS in the hot tub for a week, I shocked with MPS one week ago. I have an ozonater that runs 24/7 and a 24/7 circulation pump (325 gallon spa). The spa is outside but is almost always covered during the day and normally only uncovered and used at night. Also nearing the 4 month point of performing a drain and refill, not sure if that could have an effect on anything.

Any help on this would be great hoping to figure this out before I do the drain and refill.

[waterbear]

you have .5 ppm combined chlorine. This is what you are smelling. Shock with chlorine with the cover off and cirulaton running for about 4 hours. You need to raise your FC level about 10-12 ppm over what it is now to reach breakpoint.