### Certified Pool Operator Math Questions

**The Answers to the Math Questions on the Pool Operator Certification **test are easily the most significant cause of apprehension for students attending the pool operator certification class, but it doesn’t need to be. In this, as in any class, a little bit of preparation can go a long way towards settling nerves and thwarting pre-test jitters. The pool operator course indeed delivers a tremendous amount of information in a short time (2 days), but there is no reason that a student should stress the open-book multiple-choice test heading into, or during, the class if time has been spent preparing correctly. Besides, we do not learn very well when we are unnecessarily frazzled.

We have put the following practice/prep questions together to give pool operator certification students a taste of “Pool Math” and build a bit more confidence to hopefully nix any pre-class anxiety that may distract from the lessons taught in the course. There is a link to the answer key at the bottom of the page. **#YouGotThis**

**The surface area of a square/rectangle; Length X Width = Square Feet **

All calculations are done in FEET. If you have a diagram that is labeled in yards or meters, you must CONVERT the yards or meters to feet. To convert yards, multiply yards x 3 (there are 3 feet in each yard) to get the measurement in feet.

In this diagram, 50 yds x 3 = __________ ft

Therefore, in this diagram, to determine surface area, multiply L x W.

The surface area of this diagram is L_____ x W_____ = _____ Sq. Ft.

**The surface area of a circle. **

To determine surface area, multiply 3.14 x the RADIUS x the RADIUS = square feet. The RADIUS is always one half of the diameter. The diameter of the circle in this diagram is 12 feet. Therefore, the RADIUS is _____ ft.

The surface area of this circle is _____ X _____ X _____ = _____ Sq. Ft.

**Calculating Average Depth:**

Sometimes, we need to determine the AVERAGE DEPTH of a pool with a sloped bottom. To calculate the average depth, we do a simple ‘average’ calculation; Add the shallow depth + the deep depth, and then divide by 2. This formula will work only if the pool bottom has a constant slope – one angle from shallow to deep, as pictured here.

The average depth of this pool is _____ + _____ ÷ 2 = ______

**Calculation Gallons in a Rectangle Shaped Pool:** When we multiply feet x feet x feet, our answer is given in CUBIC FEET – therefore, if we do our volume according to the formula of surface area x average depth, our answer will be in cubic feet. However, in pools, we refer to the volume of water in GALLONS. So, once we do our surface area x depth calculation, we have to convert cubic feet to gallons. Since each cubic foot can hold approximately 7.5 gallons of water, the complete volume formula is Surface area x depth x 7.5 = gallons.

In the above pool, the length is 150 YARDS, the width is 75 feet, and the depth is a constant 8 feet. What is the volume of this pool? REMEMBER, all calculations must be done in FEET.

Convert length to feet ____ X ____ = ft. THEN do volume: _____ X _____ X _____ X _____ = __________ gal

**Calculating Water Loss:** If we have a pool and we have lost 1.75 inches of water over 7 days, how much water did we lose each day? ____inches lost ÷ ___Total Days = _____Inches Lost per day

If we have an “L” shaped pool that measures 50 meters long by 25 yards wide, with a 75 ft by 75 ft diving area – how many gallons of water did we lose if we lost a total of 1 inch?

First Calculate Surface area. In an “L” shaped pool, it is best to break the pool into 2 different components to calculate this.

Section “A” Measures 50 meters by (50 yards – 75 ft) Convert Meters to Feet: _____meters x 3.28 = _____ ft

Convert Yards to Feet: ______yards x 3 = _______ft

________ ft length x _________ft width = ________sq ft surface area

Section “B” measures 75 ft by 75 ft: ________ ft length x _________ft width = ________sq ft surface area

When calculating gallons in water lost, understand that our depth (inches of water lost) is a constant depth. There is no need to calculate an average depth as the entire pool has lost the same amount of water, equally. Add the surface area of the 2 sections together for your total surface area

___________ sq ft surface area “A” + __________ sq ft surface area “B” = ___________ sq ft surface area total

To calculate gallons, we need to have our depth measured in feet. In this scenario, we have lost 1 inch of water. To convert inches to feet, we must divide inches by 12 (there are 12 inches in a foot)

1 inch ÷ 12 (inches in a foot) = .0833 ft depth

**The Night Before the Class:** *“Warm milk is one of the best drinks that you can have at the end of the day. It’s been proven to help fight against insomnia and restless leg syndrome, largely because it helps to reduce your anxiety levels…The warmth of the liquid also plays a part. Like with the chamomile and rooibos tea, as we drink something warm, our muscles get the alert to relax. You’ll find that you don’t tense up without realizing, keeping the stress hormone release to a minimum.” – positive **health-wellness*

**Calculate Gallons Lost (continued):**

____________________ Total Surface Area x .0833 x 7.5 = _______________ gallons lost in this pool

Had we lost 5 inches of water, we would then take the gallonage calculated above and then multiply by 5.

How many gallons of water did we lose in this pool if we lost 1.75 inches of water?

__________Total Surface Area x .0833 x 7.5 = __________gallons in 1 inch x 1.75” lost = ______________gal

**When calculating volume (gallons) for a pool with multiple depths, it is best to break the pool into multiple components based off of those depths**

The example above is a 75-meter long pool by 25 yards wide with a 40-meter shallow end that slopes from 4 ft to 8 ft deep. The pool also has a diving well with a constant 12-foot depth

The Shallow end of this pool measures 40 meters long by 25 yards wide, with a constant slope depth of 4 ft to 8 ft.

First: Convert meters to feet (3.28 feet per meter)

_______meters x 3.28 = ________ ft

Next: Convert yards to feet ( 3 ft per yard)

_________ yards x 3 = __________ft

Calculate average Depth: ______ shallow end depth + ______ deep end depth ÷ 2 = _________ avg depth

Place numbers into your formula: Length x Width x Avg Depth x 7.5 = Gallons

____ length x ____ width x ____ avg depth x 7.5 = _________ gal

The Deep end of this pool measures (75 – 40 meters) long by 25 yards wide, with a constant depth of 12 ft.

First: Convert meters to feet (3.28 feet per meter)

_______meters x 3.28 = ________ ft

Next: Convert yards to feet ( 3 ft per yard)

__________ yards x 3 = __________ft

We DO NOT need to calculate the average depth in this section of the pool because it is 12 ft all the way across.

The Deep end of this pool measures (75 – 40 meters) long by 25 yards wide, with a constant depth of 12 ft.

First: Convert meters to feet (3.28 feet per meter)

_______meters x 3.28 = ________ ft

Next: Convert yards to feet ( 3 ft per yard)

__________ yards x 3 = __________ft

Place numbers into your formula: Length x Width x Avg Depth x 7.5 = Gallons

____ length x ____ width x ____ depth x 7.5 = _________ gal

The final step in calculating gallons for a pool with multiple depths is to add the gallons calculated for each individual section together – giving us total gallons of water

__________ shallow end gallons + __________ deep end gallons = ________________Total Pool Gallons

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**Converting Fluid Ounces to Gallons:**

There are 128 ounces in a Gallon, to convert ounces to gallons you will divide the number of fluid ounces by 128.

To achieve breakpoint chlorination, you will need to add 540 fl ounces of liquid chlorine to your pool, how many gallons do you need?

_____________ fluid ounces ÷ 128 = ______________ Gallons

**Converting Ounces to Pounds:**

There are 16 ounces in a pound, to convert ounces to pounds you will divide the number of ounces by 16

From your water test results, you have determined that you will need to add 60 ounces of Cyanuric acid to bring your stabilizer level from 0 ppm to 30 ppm, how many pounds do you need?

____________ ounces ÷ 16 = ___________________ Pounds

**Calculating Chemical Dose:**

If you are cooking dinner for 12 people and your recipe states that it will feed 4 people, you must triple (multiply x 3) the ingredients to prepare enough food for your guests. Making chemical adjustments to a swimming pool is very similar to cooking a meal with a recipe. Every chemical has a “recipe,” and every recipe will treat a specific amount of water, but you will not always have the same amount of water the recipe states that it will treat.

If the label on a bucket of calcium hypochlorite states that 2 ounces will raise the chlorine level of 10,000 gallons of water by 1 ppm. You have 10,000 gallons of water, but you require a 3 ppm chlorine level increase – How much calcium hypochlorite must you add?

Formula (recipe) 2 oz of Calcium Hypochlorite will raise the chlorine level of 10,000 gallons of water by 1 ppm

A. Chemical dose from label: _____

B. Gallons ÷ 10,000 = _____ A. ________ x B.__________ x C. __________ = _________ oz

C. Desired ppm increase ÷ A = _____

How many pounds is that?

____________ ounces ÷ 16 = ______________ lbs.

**Calculating Flowrate Necessary to Achieve Turnover Rate:**

A 25,000-gallon pool has a required turnover rate of 6 hours, what is the flow rate (GPM) required to meet this turnover rate?

Formula: Gallons ÷ Turnover Rate ÷ 60 = gallons per minute required

__________ gallons ÷ __________ turnover rate ÷ 60 = __________ GPM required

**Calculating Gallons in a Circular Body of Water:**

A circular spa has a Diameter of 10 feet and a constant depth of 3 feet. How many gallons of water does our spa hold?

Step 1: Calculate Surface Area

Formula: Radius x Radius x 3.14

Radius = ½ Diameter

________ Diameter ÷ 2 = __________ Radius

________ Radius x ________ Radius x 3.14 = ________ sq ft surface area

Our spa has a constant depth of 3 feet (no need to calculate average depth).

__________ sq ft surface area x _________depth x 7.5 = ____________gal

**Calculating Maximum Flow Rate Based Upon Media Ability:**

A Sand Filter has a Diameter of 5 ft and has a filter media rate of 10 gallons per minute per sq ft of filter area. What is the maximum flow rate this sand filter can handle?

Filter Area = Surface Area

First Calculate Surface Area

Formula: Radius x Radius x 3.14

Radius = ½ Diameter

________ Diameter ÷ 2 = __________ Radius

________ Radius x ________ Radius x 3.14 = ________ sq ft surface area

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**The important thing to remember as you prepare** for the CPO Certification Course is that, when it comes down to the nitty-gritty of it, this is an open book test and all of the questions are multiple-choice. Although the course itself may seem to be cumbersome math, the majority of the test will involve looking up answers in the book. That does not mean that we do not want you to learn. We are hoping that you can absorb as much as possible. We do want you to earn the certification, but the ultimate goal is to assist in making your swimming pools safer, healthier, easier to maintain, and (if applicable) your business more profitable. You are not going to remember every single thing that is said in class. The more you refer back to the materials going forward, the more you will commit these things to memory. For now, even though I want you to retain as much information as possible, I need you to remember that an open book test is simply a test on how to use the book.

## #CERTIFIED

**See how you did:** **ANSWER KEY**

**Click the Logo for a CPO® Certification Class near you:**

Hello my question. can I use my calculator ,and my pool chem calculator during this two day class? And can I bring my own notes that I have studied ?

Hey Leo – Thanks for reaching out to us! You can absolutely use your calculator (it is highly recommended) and any notes that you take. You can not use a pool chemistry app in class. You will need an actual calculator, the calculator function on a cell phone (internet, siri, cortana, google, lifeline, etc) is not permitted. We do provide handouts and worksheets, as well as hands-on opportunities, that (combined with the teaching method) will have you thoroughly prepared without the need for an app.