Is BBB method more economical?

[chem geek]

I read on this fourm somewhere that 1 pound of pool-specific granular chlorine is equal to 2 gallons of 6% bleach.

The following table gives the equivalent values for one pound of each form of chlorine and also shows the affect in a 10,000 gallon pool (with 100 ppm TA, 30 ppm CYA and 7.5 pH initially) where the pH and TA are shown AFTER the chlorine is used up (by disinfection, oxidation, breakdown from sunlight).

1 pound of...
Form of Chlorine     Equiv. 6% Bleach    FC     CYA    CH    pH      TA
1 pound 6% Bleach       0.11 gallons    +0.7    0      0     0       0
1 gallon 6% Bleach      1.0 gallon      +6.2    0      0     0       0
Tri-Chlor               1.8 gallons    +11.0   +6.7    0    -0.41   -7.7
Di-Chlor                1.1 gallons     +6.6   +6.0    0    -0.21   -2.3
Cal-Hypo                1.3 gallons     +7.7    0     +5.5  +0.77  +11.3
Chlorine Gas            1.9 gallons    +12.0    0      0    -0.62  -16.9

If the chlorine you are referring to is "granular", it is more likely to be Di-Chlor as Tri-Chlor is typically in the form of solid pucks or tablets (3" or 1" in diameter). The ingredient label should say something that makes it obvious (like "...dichloro..." or "...trichloro...").

Prices vary across the country, but it may be that chlorinating liquid from your pool store or a hardware store might be more economical for you. I am able to get 12.5% chlorinating liquid for $2.50/gallon so the price of 6% bleach would need to be less than about $1.25/gallon to be equivalent. So you may find that you can find a better deal for chlolrinating liquid than bleach in your area (and you'll carry less weight for the same amount of chlorine).

As for using a lot of chlorine because of the size of your pool, that is very true though having a pool cover will help cut down consumption considerably. Because of my electric pool cover, I only use about 0.5 ppm or less of chlorine per day so that's about 1 cup of 12.5% chlorinating liquid per day in my 16,000 gallon pool. Of course an SWCG system is the easiest method of generating chlorine of all (and like liquid chlorine, has no CYA nor CH increase and is fairly neutral in pH though most users see a pH rise possibly due to carbon dioxide outgassing from the aerating hydrogen bubbles that are produced by the SWCG). Another way to reduce chlorine consumption is to add Borax to your pool to get to 50 ppm Boron content (see this thread for more info on how Borax reduced chlorine consumption by acting as an algicide so that chlorine didn't have to).

Richard