Oxidizers - Do They Work ?

[chem geek]

Greg,

That's just B.S. The ingredients in bleach and in lithium hypochlorite are virtually identical except that the hypochlorite in bleach is sodium hypochlorite while the sodium is replaced by lithium in the powdered product. They both have the same percentage of salt. There are no extra additives in lithium hypochlorite or Dichlor to protect spas. That's just baloney, at least for every product that I've seen -- they don't even claim as such as far as I could tell. Perhaps they mean the CYA in Dichlor, but I'll talk more about that later and is why you start out using Dichlor first before switching to bleach.

ALL sources of chlorine produce the identical chlorine in the water -- hypochlorous acid -- but they vary in what they additionally add. Bleach and lithium hypochlorite also add salt. Dichlor and Trichlor both add Cyanuric Acid (CYA). Cal-Hypo (for pools, usually) adds calcium so increases Calcium Hardness (CH). Even though bleach and lithium hypochlorite add salt upon addition, ALL sources of chlorine will result in salt since the chlorine gets used up and converts to chloride salt.

As for pH, bleach and lithium hypochlorite increase pH upon addition, but the consumption/usage of chlorine is acidic so they are essentially pH neutral -- pH rise in spas is mostly due to carbon dioxide outgassing which is made worse at higher Total Alkalinity (TA) levels. So using Dichlor only is not pH neutral and over time results in the pH dropping unless there is sufficiently high TA and aeration to keep the pH in balance or even rising in which cases over time the TA slowly drops.

What IS true is that if you were to start out using bleach by itself as your sole source of chlorine, then you would have no CYA in the water and that would make the chlorine too strong and too harsh on spa covers and equipment. This is the main reason why spa manufacturers/dealers say not to use bleach (though technically, using only lithium hypochlorite would cause the same problems). However, using Dichlor initially for about a week or so will build up the CYA level to around 30 ppm after which you can very safely switch to bleach. The CYA moderates chlorine's strength cutting it down significantly by at least a factor of 6 or more at that CYA level and at high 104F spa temperature (at lower temps near 77F the strength is cut down by a factor of 33).

As with any concentrated chemical, you want to add it slowly over a return flow with the circulation pump running. Don't have the jets on as you don't want to splash the chemical back into your face.

If you are truly concerned specifically with using bleach, then you could replace the bleach with lithium hypochlorite, but still start out using Dichlor. This will cost you a lot more as lithium hypochlorite is at least 5 times as expensive as bleach or chlorinating liquid for the same equivalent FC level (see this link for details). One advantage to using the lithium hypochlorite is that it is less likely for you to spill any on your clothes -- some people have a hard time with bleach spilling or splashing it onto their clothes, which of course ruins them by bleaching them out (the same would happen with lithium hypochlorite or any other source of chlorine, but being a powder it doesn't "spread" as quickly unless you were to add water).

Richard

[Nitro]

BTW, I did go to the "pool store" and get my water tested the other day and had a chat with the "pro" about using bleach. He didn't say not a good idea at first but then warned me that I could potentially void the warranty on my spa. He mentioned that there are other things in bleach (not specified) that can harm or "pit" the jets and damage the chrome. That bleach is highly corrosive and could damage the metals in the pump etc. He also said there are things added to the chlorine products that help to protect the hot tub parts.

hmmm....

When I look at the bottle of bleach it has the same warning symbols as my chlorine. Don't drink it basically and careful not to splash it in your eyes or on your skin.

I am using the standard 6% bleach. All is says is sodium hypochlorite.

Greg

Sounds like a typical response from a "pro" at a "pool store". You could print THIS out and give it to him. Maybe he'll have an open mind and learn something. But even if he does he'll probably ignore it, because it's not good for business.

[quantumchromodynamics]

Greg, the so-called "pool store pro", who told you those things, is completely wrong. Ask them to provide the specific details, including the actual chemistry equations involved. He has no basis for the things he said. If he really knows what he is talking about then he should have no problem providing the requested information.