Chlorine question

[AnnaK]

Chlorine concentration does degrade over time. It ap[pears to be related to temperature. Here's a link: http://www.odysseymanufacturing.com/about_product.htm. At the bottom of that page is a link to shelf life of chlorine at different concentrations.

I buy liquid chlorine which is said to be 14% when manufactured. I've tested it a couple of times and have come up with something between 10 and 12%. I use 11% when I calculate how much to add to my pool. When I have chlorine left over at the end of the season I don't actually care what strength it is at startup. I just pour in what's left because I know the pool will be at 0 FC.

[waldreps]

Thanks for the reply. I should probably buy one and test it to get an idea about it's strength before buying a bunch of them. They normally have this priced at $3.99 per gallon but now have it on sale at 4 for $10. I'm guessing at $3.99 per gallon they don't sell a lot of it so it's probably been sitting there for a long time.

[AnnaK]

Being a cynic I would have to agree. A drop fro $3.99 to $2.50, which is less than a gallon or regular bleach, likely means it's old-y and moldy. Testing bleach to get its actual concentration can be a bit of a PITA. You can use the shot glass method and get an approximation, or you could just buy a gallon, test your pool before you put any in, put in 2 quarts, and test again after a couple of hours. If you're using a DPD-FAS test kit you'll get a good idea of the strength of this bleach. Just be sure to read the label: you do not want scented or gel'd or anything but sodium hypochlorite.

[waldreps]

Yeah, this is called Clear XTreme Pool Shock. The label says 15% available chlorine and 12.5% sodium hypochlorite. I'm assuming this would be considered 12.5% concentration. I'm not sure what the 15% available chlorine part means.

[AnnaK]

I don't either and I don't really believe an effective concentration of 12.5% at time of purchase. A quick Google search does seem to indicate it's a common bleach product sold for pools and listed by the EPA as Hypo 150. Menard's, a big box hardware store in the south, sells it for $1.99 a gallon if you have a coupon.

[waldreps]

This is at Menard's, but unless I'm mistaken Menard's is only in the Midwest. $1.99 per gallon would be an awesome price though.