waterbear Posted March 22, 2021 Report Share Posted March 22, 2021 If you use the Metric system 1 tablespoon is approx. 15 ml and every 19 liters of water in your tub is approx 5 gallons. These values are close enough for practical use. For every 100 gallons (380 liters) of water adding 1 tablespoon (15 ml) of: 5.25% bleach will raise FC by about 2 ppm 6.0% bleach will raise FC by about 2.5 ppm 8.25% bleach will raise FC by about 3.3 ppm 10.0% bleach will raise FC by about 4 ppm 12.5% bleach will raise FC by about 5 ppm I have just learned that there is also 7.5% bleach being sold so I would expect the 7.5% bleach will raise FC by about 3 ppm (these numbers are not exact but are in the ballpark. They have been rounded to make measurements easier but should be close enough to get you where you want to be or very close to it) 10% and 12.5% bleach are normally sold as "liquid pool chlorine" 6% laundry bleach is usually called "ultra bleach" If you are using laundry bleach you want the plain,unscented, one with NO thickeners, detergents, or scents. The ingredients might list water, sodium hypochlorite, sodium chloride (salt), sodium hydroxide, sodium carbonate, and (for laundry bleach) polyacrylic acid (used to prevent soil from redepositing back on clothes and is also the main ingredient in many polymeric pool and spa clarifiers so the small amount in the bleach will NOT have any negative impact on your water). These are either added to stabilize the bleach or are the result of the manufacturing process and are a normal part of the makeup of bleach or liquid chlorine. The ONLY differences between the different strengths of sodium hypochlorite is how much is needed to reach a given FC level in a given volume of water and the shelf life of the bleach. The more concentrated strengths need less to achieve a given FC level in a given volume of water and have a shorter shelf life before they start to degrade and lose strength. There is no reason you can't use old bleach as long as you are testing the FC and adding enough to achieve the desired level. 2 1 Quote Link to comment Share on other sites More sharing options...
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