Eniromental Health: Calculated Chlorine Content Needed in a Pool

Solution:

You can handle this problem just as you would a percentage mixture problem. A ppm expresses a number out of a million whereas a percentage is a number expressed out of 100.

Let x = the amount of pool water in liters that needs replacing with chlorine-free water.

	Pool Mix	-Pool Mix	+Pure Water	Final Pool Mix
ppm(chlorine)	4.5	4.5	0	1.5
Vol. of Pool Mix	81600 L	-x	+x	81600 L

The following equation describes volumes of chlorine. It states that the initial volume of chlorine in the pool minus the volume of chlorine removed plus the volume of chlorine added equals the final volume of chlorine in the pool:

81600 (4.5 ppm)- 4.5x + 0 x = 1.5 (81,600)

0.3672 - 0.0000045 x = 0.1224

Solving for x gives:

x = 54, 400 L

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