Powdered Bleach - Will it work?

[aquarium]

Someone asked me today if I used liquid or powdered bleach. I said liquid, but it raises the question: Is there a pure form of dry sodium hypochlorite?

[chem geek]

There is a somewhat pure sodium hypochlorite solid form but it is not commercially used and I can't find a source for it. However, this isn't what someone talks about when they are talking about "powdered bleach". Powdered bleach is made from hydrogen peroxide so is an oxygen-based oxidizer. Clorox 2 powder, for example, is made by combining sodium tetraborate (yes, that's Borax) with hydrogen peroxide to produce the active ingredient sodium perborate monohydrate (most of Clorox 2 is Sodium Carbonate which is Soda Ash). This is still an oxygen-based bleaching substance.

So, bottom line, powdered bleach doesn't provide chlorine. It is similar to adding hydrogen peroxide to your pool. It is a disinfectent, but though it has a higher oxidation potential than chlorine, it doesn't last as long, etc. (peroxides are very unstable, which makes them good for disinfection, but bad for hanging around). Typically, peroxide can be used for disinfection of a specific water flow, similar to ozone or UV light, but not for the bulk pool water. So, no, you can't use oxygen-based powdered bleach as a substitute for chlorine-based liquid bleach.

Richard

[aquarium]

Thanks Richard,

By now I know that we humans are pretty good at finding the most effective way of doing things at the lowest cost. So it didn't make sense that we're stuck with liquid bleach if there were a dry alternative that is more potent at lower weight/volume/packaging cost. I suspect the dry version must have some very nasty characteristics that make it impractical to use.

[waterbear]

There is a dry chlorine bleach available. It's been around for many years and we DO use it in pools....it's calcium hypochlorite! It was used many years back as 'bleaching powder' or 'chloride of lime' as a bleach for cotton clothes but has been replaced in that use by sodium hypoclorite. (lithium hypochlorite is also a powdered form of chlorine for pools but is very expensive!)

[chem geek]

Thanks Evan. My one-track mind was thinking only of sodium hypochlorite. Of course there are the solid alternatives you mention. I think, however, that when the person asked the question about "powdered bleach" they probably meant literally what is advertised as powdered bleach such as Clorox 2 (I know you were responding to Tom's comment that we were "stuck with liquid bleach"). So now, thanks to you and I, Tom has a complete answer to cover any bases!

Richard

[Spensar]

Sounds like 12 pack of tabs that Walliemart sells, and each makes a pail a "bleach" by adding to water.