## CALCULATING THE WATER CAPACITY OF YOUR POOL OR SPA BY VOLUME OR FILL TIME

CALCULATING THE WATER CAPACITY OF YOUR POOL OR SPA BY VOLUME OR FILL TIME

Hey, no need to be embarrassed if you’ve forgotten all those mathematical equations from your high school days. After all, most of us don’t use them every day, anyway.

For pool and spa owners, however, some geometry and conversion rates are necessary to know in order to properly perform basic maintenance tasks.

For example, to regulate the chemical balance of the water, or control the temperature, you must first know the water capacity of your pool or spa; and in order to know that, you must first figure out the VOLUME of your pool or spa, measured in cubic feet. Then, this number is simply converted to gallons in order to express the unit’s water capacity.

So, here are the necessary math formulas for Calculating the Volume of your pool or spa:

1) If the pool or spa is rectangular or square, measure in feet its Length, Width, and Depth; then

VOLUME = LENGTH X WIDTH X DEPTH;

2) If the pool or spa is a circle, measure in feet its Diameter (from one side to the other); then

VOLUME = 3.14 X RADIUS² X DEPTH

(Did you remember that the Radius is half the Diameter?)

3) For pools or spas which are shaped like an oval, measure in feet both Diameters; then

VOLUME = 3.14 X FIRST RADIUS X SECOND RADIUS X DEPTH

Now, simply change “cubic feet” to “gallons” to determine the Water Capacity of your pool or spa by multiplying the above answer by 7.48 as the conversion rate below indicates. For example, a pool that has a Volume of 10,000 cubic feet would have a Water Capacity of 70,480 gallons since 10,000 X 7.48 = 70,480.

One (1) Cubic Foot of Water = 7.48 Gallons

One (1) Gallon of Water = 0.134 Cubic Feet

Now, this measurement isn’t going to be exact since most pools and spas have sloping floors and walls. So, for a much more accurate measurement, determine the Water Capacity by Fill Time, when your pool or spa happens to be empty.

Use a stopwatch to time how long it takes to fill your pool or spa; then, using the same hose and water pressure, time how long it takes to fill a five-gallon bucket, as well. Simply compare the two measurements to create a useable conversion rate from buckets to gallons, and you’ll have your answer.

In other words, if the bucket takes 30 seconds to fill and your spa takes 30 minutes (1,800 seconds) to fill, then you could conceivably fill 60 five-gallon buckets in the same amount of time it takes to fill your whole spa, right? (1,800 seconds ÷ 30 seconds = 60 five-gallon buckets) Therefore, the water capacity of your spa is 300 gallons because 60 total buckets X 5 gallons per bucket = 300 total gallons.

In the same way, if the 5-gallon bucket took 30 seconds to fill and your pool took 10 hours (36,000 seconds) to fill, then the water capacity of your pool would be 6,000 gallons.

So, it’s not even necessary to remember all those geometry formulas from high school in order to calculate the water capacity of your pool or spa. I just wanted to include them in this article so that now you may actually be able to help your kids with their math homework.

June 23, 2017 at 9:12 pm Comments (0)