I think most stay under 4ppm chlorine.
Consumer laundry bleaches are typically 3-10% active chlorine
. So if you added 1.3 ounces of a generic bleach with 3% active chlorine to a full 100 gallon tank of water, it would result in about 3ppm chlorine. If you added 1.3 ounces of Clorox Ultra, then it would result in 10ppm.
Take a close look at a bottle of Clorox or other bleach on the supermarket shelf. Most are 6% Sodium Hypochlorite. Chlorine purchased at Home Depot, etc. for swimming pools usually is 10%, and the stuff I get from the pool wholesale house runs 12%.But -
Liquid chlorine deteriorates rapidly when exposed to sunlight. If I run around with a case of liquid in the back of my truck for a week, that 12% will be down to about 9 or so. If I don't use it up, by the end of the month, it's virtually useless - even in the opaque bottles. Moral: keep bleach containers out of direct sunlight to maintain potency.
Swimming pool water is typically maintained at 1 -3 ppm of chlorine average year-round. I will bump some of my customer's pools to 3 -5 ppm due to heavy usage in the summertime, then let it drift back down to 1 -3 for fall/winter/spring.
Wayne's comments about municipalities using chloramines for sanitation brings up another point. If you get out of a pool and "smell like chlorine", what you're smelling is actually chloramines - often formed when kids pee in the pool. (Combination of chlorine and organic compounds, actually) Those of us in the pool industry have found that excessive chloramines in pool water actually reduce
the effectiveness of chlorine as a sanitizer, and must be dealt with by adding
additional chlorine into the water to break the organic bond and allow the free chlorine to provide the sanitation necessary. (AKA "Superchlorination")
Sodium Bicarbonate (baking soda) is used by the pool industry to help balance alkalinity, which acts as a buffer to help control the pH of the water, with 7 pH being neutral (acid/base balance).
How does this relate to fresh water tanks? My point is that if you keep the chlorine level in your tank to that of a pool (1-3 ppm), you shouldn't have any problems. This does require that you either a) do the math to figure out how much bleach to add specifically for your tank size, or b) buy some test strips at a pool supply store and test your water (run some tap into a bowl) and adjust as necessary.
FWIW & HTH. . .