How many pounds of 70% pure HTH must be added to a 2 million gallon tank for disinfection at 50 ppm?

To determine how many pounds of 70% pure HTH (calcium hypochlorite) must be added to a 2 million-gallon tank for disinfection at a concentration of 50 ppm (parts per million), we need to start by calculating the total amount of disinfectant required.

First, we convert the volume of water to gallons, which is 2,000,000 gallons. Since 1 ppm is equivalent to 1 mg/L and there are approximately 3.78541 liters in a gallon, we can convert gallons to liters:

[ 2,000,000 \text{ gallons} \times 3.78541 \text{ L/gallon} \approx 7,571,000 \text{ L.} ]

Next, to find out how many milligrams of HTH are needed for a concentration of 50 ppm, we multiply by the volume in liters:

[ 50 \text{ mg/L} \times 7,571,000 \text{ L} = 378,550,000 \text{ mg.} ]

Since we need the amount in pounds, we convert milligrams to pounds. There are 453,592 mg in a pound:

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