hi eartha,

i have the same size pool, so i can help you out. (i'm also a mathematician, which helps, although i'm not a major geek so get that thought right out of your head.)

anyhow, if you're using "ultra" bleach, which is what most bleach is now (6% chlorine), a full 96oz. bottle will raise the chlorine level in your pool by about 1.8 PPM. if you're using "regular" bleach, which is 5.25%, in the full gallon jugs, each full bottle will raise FC by about 2.1 PPM. if you're using "liquid chlorine" marketed for pools, most of which is 10%, a full gallon jug will raise the FC by about 4 PPM.

so after testing if you find that you need to raise the FC by 1 PPM, that would be about 53 oz. of ultra (6% bleach), about 61 oz. of regular (5.25%) bleach, and about a quart of liquid chlorine (10%).

the frequency at which you'll have to add these amounts depends on a variety of factors, the most important of which are swimmer load and sunlight that the pool gets. i've found that keeping my solar cover on when we're not in the pool cuts the chlorine demand at least in half, so if you're trying to save, that's a good option. on average, when i was using ultra bleach, i would put in about 48 oz. each night, which worked out to about half a buck a day. not bad!

for what it's worth, in my area (SW ohio), the best buy in terms of PPM per dollar is the 10% liquid chlorine at meijer, which they sell for $10 for a case of 4. the 96 oz ultra bleach bottles at cheap places like aldi used to be best, but the price went up and meijer is the new winner.

one final thing: ALWAYS check the label when buying bleach to see what the concentration is. some cheesy bargain brands have been reported to go as low as 2.5%. if it doesn't list the concentration, don't even think about buying it.

hope that helps.

ps - our dogs swim in the pool constantly, and have never shown any ill effects, even the morning after shocking when the FC might be close to 10.