Household Bleach

PPM should have also V or W (volume, or weight) added, because these are different numbers and not both mg/l equivalents. (here PPMV when referred to liter)

I have just become interested in the subject of bleach strength because I thought I could save a bit on money by buying it by the gallon instead of numerous typical kitchen sink sizes. Your name popped up in a search on CR4.

I do not need to get an exact measure of concentration, but more an indication of strength when comparing prices. Normally the label says so, but in the case here of two identical bottles, one of 'thick' bleach it says 'less than 5% sodium hypochlorate', compared to another bottle of 'thin' bleach which says exactly the same!

I bought both. The 'thin' bleach was runny and seemed weak, when compared to the 'thick' bleach, which did not seem any stronger but was not as runny - more of a gel like consistency.

Being cynical, 'less than 5% sodium hypochlorate', could be normal bleach that has been diluted to make it thin - and therefore an expensive way of buying water. Or could the 'thick' bleach also be diluted bleach but with gelatine added - another expensive way of buying water but with some gel into the bargain.

I thought that I had read somewhere that 5% was standard for household bleach. If you have access to pool bleach, that is 10% I think. And the pellet type of pool bleach might allow stronger concentrations. Not sure, but a refractometer is a common device for measuring concentrations of water based fluids. This might be helpful. Good luck.

In my experience working on medical equipment for years, the 'thick' bleach is that consistency because of adding a surfactant (soapy?).

With out analyzers, the surfactant coated surfaces and caused much trouble. The same can be said for the 'scented' bleaches, full of smelling oils.

I think any household bleach is 5% in the jug, and it is most effective when that is used in a 10% bleach and 90% water solution.

Thanks Bob and Sid (18 and 19).

As the label say "less than 5%....." Being cynical this could mean 1 or 2%. I suppose both, thick and thin, could be watered down standard bleach of 5% for our local supermarket to get the price right.

I will look for a bleach that has an unambiguous label.

You should store it in the freezer, or keep it as cool as possible...

All bleach decomposition is dependant on temperature. For any given temperature, the higher the

strength, the faster it decomposes. In order to completely understand the decomposition of bleach with

respect to strength versus temperature please refer to the AWWA research document "Minimizing

Chlorate when Hypochlorite is the Chlorinating Ion." In summary, for every 10° C increase in storage

temperature, the sodium hypochlorite will decompose at an increased rate factor of approximately 3.5.

The American Water Works Association (AWWA) website is currently down with a CFML Runtime Error, meaning that something is amiss with the MYSQL database that runs the site. So the document, Minimizing Chlorate when Hypochlorite is the Chlorinating Ion, is temporarily unavailable.

Although cooling the solution decreases the loss of activity over time, it is inadvisable to freeze it, because some of the Sodium Hypochlorite and some of the Sodium Chloride may come out of solution.

This is from White's Handbook of Chlorination and Alternative Disinfectants, courtesy of Google Books.

Freezing of the solution generally does not affect its quality after it is thawed; however, freezing of sodium hypochlorite expands its volume (similar to water), so freezing inside piping, valves, pumps, or tanks can cause significant damage to equipment. In some cases, it may result in precipitation of sodium chloride and/or sodium hypochlorite from the solution and fouling or clogging of pumps, piping, and valves. Care should be taken with thawed hypochlorite solutions to ensure that precipitates are not present.

Also see the Sodium Hypochlorite-General Information Handbook

The similarly titled Sodium Hypochlorite General Information Handbook repeats some of this information, but is a different document. Good luck.

Sodium hypochlorite, stored as a liquid, degrades over time. Calcium hypochlorite, stored as a solid, has much better stability. "Horses for courses"?

Another way to look at it is akin to the "use by" or "best before" dates on the manufacturer's packaging around foodstuffs. It is there to protect the manufacturer. It is also there to prompt the end-user to dispose of stuff that is beyond date before it gets used, and replace it with new stuff.

Cynical or what?

Your cardboard test looks OK to me.

If you just want to know whether your bleach is strong or weak and not quantified then this sort of rough "litmus" test that can be performed without special equipment, reagents or training might be the go.

If you want to dilute neat bleach for your requirements then the pool test kit is the most accessible setup but you may have to dilute your sample with water in a controlled way to have a test sample that is within normal pool water chlorine concentrations.

Can you not make your own liquid bleach with granular chlorine and water to your required concentration? Alternatively buy less (liquid) bleach more frequently......

I don't know if what I am saying is true, but it might be possible to design a small meter with a probe, that measures the temperature of the liquid and the exact current that can flow at a particular voltage. This current will probably vary only very slightly with the change in quality and exact measurement will probably be needed.

Then build up a table of current to quality, with a temperature correction built in. Measure the current, & the temperature and simply look it up.

A PIC would do all the "fiddly" work for you......but as I implied earlier, no guarantee that it either works or will be easy to design, but it may be a way to go for a quick reading!!

The result may even be marketable.....best of luck.

Look here:-

http://www.lamotte.com/pages/common/pdf/instruct/7894-dr.pdf

This the conventional method of laboratory testing.....

can you buy the crystals that are used for hot tubs and spas and then just mix up the quantity your need when required.

i really don't know if it is the same "bleach" or not , but it smells te same..

Here are some thoughts for discussion. Because we do not know the quantity, or frequency of your bleach use, would buying powered chlorine from pool supply stores be more practical? As for measuring the strength of the chlorine, refractometers are available at very reasonable costs. 5.25% bleach solution reads roughly 10 on a standard brix scale. When diluted, it drops rapidly. What I do not know, is weather the reading will drop as the bleach decomposes.I have an inexpensive digital refractometer that I use regularly, and it has impressed me with its reliability over the last 5 years.

Sounds like a good machine for the OP, what does one cost?

I thought this was about $100. This brand was Atago, at www.atago.net. Previously we were using optical refractometers, and were less exact, and subject to interpretation of the used. And fragile.

I wonder if the price is OP acceptable....

Thanks for your reply.