With the Corona-virus outbreak closing schools across the country, and shelter-in-place orders or recommendations issued, parents are having to create fun and interesting activities for their children.
For those parents with a pool, you have the perfect teaching tool for lessons in all areas of S.T.E.A.M. (Science, Technology, Engineering, Arts and Math).
These lessons are great for home-school kids, as well as for those temporarily home schooled, during the COVID-19 closures, or for any kid during summer vacation.
Science in the Pool
Swimming pools are full of science, but let’s limit this to Chemistry and Biology. With chemistry, of course we are speaking of pool water chemistry, and your test kit or strips. Conduct a lesson of pool water tests, one at a time, and discuss the what and why of each test.
Free Chlorine: Keeping your water sanitary and dis-infected during these times is crucial. Free Chlorine is a measurement of the chlorine molecules that have not expended themselves, or bonded with other compounds or elements, such as nitrogen or ammonia. When such chlorine bonds are made, this converts Free Chlorine into a Combined Chlorine molecule, or a Chloramine. Chloramines are not effective against viruses and bacteria, and they have a strong chlorine odor. Shocking the pool with large amounts of chlorine, will destroy the Chloramines and remove the strong odor and itchy, red eyes. Only DPD test kits have the ability to test for both Free and Total Chlorine, and any difference between the two is the amount of Combined Chlorine in the water.
pH: pH is a measurement of the level of acidity or basicity in your pool water that uses a scale from 0-14. A pH of 7.0 is neutral, neither acidic or basic, and levels lower than 7.0 are acidic and levels above 7.0 are basic. Every liquid on earth has a pH value, some more acidic like soft drinks, and some more basic, like milk.
The level of pH in your pool water affects the efficacy or potency of the chlorine in the water. As pH levels increase, the activity level of chlorine decreases; they become tired and sluggish, like sleepy kids. The level of pH in your pool also affects the underwater surfaces of your pool – consistently low pH levels are corrosive to the soft and shiny surfaces, etching and pitting plaster, vinyl, chrome and copper. High pH levels are also a problem, and creates a scaling condition, making pool stains and calcium deposits.
Total Alkalinity: A close cousin to pH, Alkalinity is a measurement of the alkaline substances in the water, which provide a buffer to the pH level. When the Alkalinity level is low in the pool (< 80 ppm), the pH level can become unstable and fluctuate wildly, even after adding pH adjustment chemicals. When Alkalinity is high in the pool (> 150 ppm), the pH level can be hard to adjust; it becomes overly stable and fixed. Alkalinity levels are increased by adding Sodium Bicarbonate (Baking Soda), aka Alkalinity Increaser, and levels are lowered by using pH decreaser or other liquid or dry acid.
Calcium Hardness: A measurement of how ‘hard’ or ‘soft’ the water is, or the amount of calcium in the water. Pools with soft water (< 150 ppm) tend to foam and cloud more easily, and underwater pool surfaces can be damaged. Pools with hard water (> 500 ppm) tend to scale more easily, especially when the pool has high pH levels, creating calcium deposits, in thin layers or in crystalline form. Calcium Hardness levels are increased by adding Calcium Chloride, aka Calcium Hardness Increaser. Reducing hardness levels however, is not so easy, but can be accomplished by dilution, or draining and refilling a portion of the pool.
Total Dissolved Solids: Known as TDS, this is a measurement of everything that has ever been dissolved in the pool, including dust and dirt, pool chemicals, and bather waste such as skin, hair products or cosmetics. TDS is not commonly tested for pools, usually a last resort test, I mention it here because it makes a great kitchen experiment – adding salt or sugar to water slowly, one tablespoon at a time. The water will absorb the solid – until it reaches a point of ‘Saturation’, when the water cannot absorb more solids. Science!
- Have your students take over water testing for a week, testing each day and recording results in a log book. Extra credit for calculating adjustment dosages.
- Have your kids on deck while you apply water balance adjustments, modeling safe chemical handling and discussing effects of each addition.
- Quiz: If your water hardness was 800 ppm, and your tap water is 200 ppm, how much water would you need to replace to lower hardness to 400 ppm?
- Perform the saturation experiment mentioned above in the TDS section. Expand it to include salt, sugar, flour, rice, coffee, gummy bears… have fun!
- Find calcium scale on your pool tile or stonework and explain how calcium scale can come out of solution (or evaporate), and deposit on surfaces.
There’s a whole lot of biology going on in swimming pools. Looking at any drop of water under a microscope, you will find a whole host of micro-organisms, even in sanitary and properly maintained pools. What you should not find are pathogens – bacteria or viruses that can make you sick.
As we emerged from the primordial ooze, we have water to thank for allowing a molecular soup to develop the earliest forms of cells and DNA. It is the natural order for water to create life, e.g. algae and bacteria (most of which are not pathogenic). In natural water systems, plants, circulation and aquatic processes establish an equilibrium that keeps lakes and rivers from becoming unhealthy.
Pools that are properly maintained, with effective daily filtration, sanitation and circulation are safe to enjoy, without fear of contamination from bacteria, viruses or parasites.
- If you have a microscope, look at a drop of pool water, and compare it to a drop of water from a rain puddle. Make a drawing of each on paper.
- Place an ounce of water on the kitchen window sill, and each day look at a sample drop of water with a microscope. Draw a picture each day, and use online research to label the micro-organisms identified.
- Discuss the deterioration of your pool water if you were to shut-off the pump and stop managing the water chemistry, during the hottest weekend in August. And in December?
- Discuss natural water systems, and natural pools. How are plants and natural filter systems used to keep water (relatively) clean and clear?
Technology in the Pool
Swimming pools of today have quite a lot of mechanical and electrical technology, some old and some new, but all can be used to create ‘teachable moments’ for your kids.
Plumbing: In a pool plumbing system, there are pipes that bring water from the pool (suction pipes), and one or more pipes that take water back to the pool (return pipes). Pool valves are used to control the direction and volume of water flow, to and from the pool, and in and out of filtering, heating and chlorinating equipment. Most pools use 1.5″ or 2″ PVC pipe to circulate the water, and either 2-way or 3-way valves to control direction and flow.
Electrical: The pool pump has an electric motor that spins an impeller to create suction and pressure – the water is under vacuum before the impeller, and under pressure after the impeller. Pool pumps can operate with 110V or 220V power, with most inground pumps hard-wired with 220 volts, and most above-ground pumps equipped with a 110 volt power cord. Most pumps are connected to an electric timeclock, because you won’t need to run the pump 24 hours per day. Timeclocks are connected to a circuit breaker in the sub-panel, and the sub-panel is connected to a much larger circuit breaker in the house main-panel. Got an electrical problem? “The problem lies where the power dies!”
Other electrical around the pool can include underwater pool lights, automatic pool cleaners, salt chlorine generators, pool heaters and pool controllers.
Heating: If you are lucky enough to have a pool heater, you have another teacher. Gas pool heaters operate in the same way as home heating furnaces or hot water heaters. They use a gas burner to heat water that is pumped in and out of the heater. Like a home heater, they are thermostat controlled, just set the temperature you want, and the heater will turn on and off, to maintain the temp. And like your home heater, pool heaters also have safety circuits like a pressure switch, to make sure water is flowing properly, high limits switches, to make sure the water does not get too hot, and other sensors to monitor flame, exhaust and pilot light.
You may also have a pool heat pump, an air-conditioner that operates in reverse to pull heat out of the surrounding air, and add it to your pool water. Solar pool heaters are also popular, absorbing the heat from the sun, and transferring it to your pool water. Science!
Cleaning: Automatic pool cleaners have been around since the early 1960’s, but the technology has improved ten-fold from the early days. At first, they were just ‘stirrer-uppers’, using long tentacles that sprayed water over the pool floor, to lift dirt and debris so that it may move closer to the skimmer or drain, and eventually be sucked into the filter. Modern pool cleaners can clean the pool in under two hours, and are able to adapt to variations in pool shape and depth.
Three types of cleaners exist nowadays, pressure cleaners which operate on water pressure pumped to the cleaner, suction cleaners which connect to a suction line like the pool skimmer, and robotic cleaners, which are not powered by the filter pump, but have their own on-board vacuum motor and propulsion systems. Pool cleaners are super interesting to just about everyone!
Chlorinating: Keeping a constant and consistent level of chlorine in the pool, good water balance and daily filtration, will keep pool water blue and clear. If you have a tablet chlorinator, give your student a short lesson on how the erosion tablet feeder works. If you have a saltwater pool, the conversation becomes much more interesting. Using electrolysis, the salt system converts the slightly salty water into pure chlorine, right inside of the pipe. And the best part is, after the chlorine has done it’s job, it converts back to salt again! Fully sustainable with just small booster treatments of salt each year.
Automation: For pools and spas, there are pool controllers that can make certain functions automatic. Pool Controllers from Jandy, Hayward and Pentair allow you to control your pump, heater, lights and valves from a remote location such as a wall-mount panel, or your smartphone. Praher makes automatic backwash valves for sand-filters, which operate on a selected time schedule, or at a specific tank pressure.
Chemical Controllers are also available to control chlorine levels and pH levels, optimized with ORP sensors. ORP, or Oxidation Reduction Potential, measures the conductivity of the water, to consistently sanitize at the most efficient level, with the lowest level of chloramines and other disinfectant byproducts being produced.
Supplemental Sanitizers: We used to call them alternative sanitizers, but they aren’t quite powerful enough to be stand-alone systems. The use of Ozone, Mineral Purifiers and the new kids on the block, UV Systems and Hydroxyl Radicals, work great as supplements, cutting your chlorine use in half. Ozonators create ozone, a molecule of three oxygen atoms, and inject the O3 into the pool’s return line pipe. The O3 molecule will zap anything it contacts, until it reaches the water surface and floats away.
Mineral purifiers from Frog and Nature2 use an erosion cartridge to introduce trace copper and silver into the pool, known bactericides and algaestats. UV systems for pools use ultraviolet light in the germicidal spectrum of 254 nm, bathing pool water in the blue light for milli-seconds, to zap 99% of impurities. Hydroxyl Radicals are a combination of Ozone and UV systems which are part of an Advanced Oxidation Process, the newest member of the club.
- Have your students draw a picture of the pool equipment, with all pipes, valves and equipment shown and labeled.
- Have your students write a paragraph on each piece of pool equipment, describing what it does and how it accomplishes the task, or a full-page report on a single equipment.
- Choose one of the supplemental sanitizers listed above, compile some online research and write a full-page report on a new pool sanitizer technology.
- Brainstorm a new pool technology, or improvement to an existing product. Can be a toy, float, game, or any accessory, equipment or chemical. Older students can draft a plan for funding, patenting, production and marketing of the (pretend) product.
- Brainstorm a new pool app that can be used on a smartphone or tablet. Search existing apps available, and develop a plan for new app, or improvement to an existing app.
Engineering in the Pool
A swimming pool without modern engineering is doomed to failure, and could be very unsafe. This is why pools are built to the principles of best practices and standards, and each one is permitted and inspected, to ensure the pool public’s safety.
Engineers are needed to create every component of a swimming pool, inground or above-ground. Every part or piece of your pool was originally created by hydraulic, mechanical and electrical engineers. Every piece of pool equipment; pumps, filters, cleaners, heaters, skimmers, etc. – all were invented and perfected by engineers. And during pool design and construction, soil engineers or structural engineers are often needed in special situations, to advise on materials and best construction practices.
- If you have them, pull-out the original specs and plans for the pool. Most inground pool owners have a ‘pool folder’ in the back of their filing cabinet. Students can color in the plat or plan to visually identify all elements of the plan, including deck, drainage and easements shown on the plat. Grading plans, spec sheets and design drawings can also be studied, to gain a better understanding of the professionals involved in building a pool.
- Your children may have been around when the pool was built, or maybe not – but the understanding of exactly how a pool is built is an interesting bit of knowledge. If your pool is concrete, check out Gunite Pool Construction Phases as a teaching guide, or for inground vinyl pools, see our Category: Build Your Own Inground Pool. For above-ground pools, see this guide to Above-Ground Pool Installation.
- For kids in the pre-teen years and older, delving into the inner workings of a pool cleaner can be very interesting. With a schematic in-hand, and just basic hand tools, have them dissassemble the pool cleaner carefully, and then put it back together again. Extra points for using a Polaris rebuild kit, or replacing some needed pool cleaner parts.
Art in the Pool
You may not have thought there is much “Art” in your swimming pool, but every pool, even the most basic, have some design elements, used to appeal to our artistic nature. It could be the shape of your pool, or the use of a specific tile pattern. Pool liner styles and patterns compete to produce attractive designs that evoke a theme or act as a focal point.
Some pools have stonework or tile mosaics of such beauty that it elevates the pool to the realm of high art, while other pools have a very artistic landscape design. Indeed, some pools are built specifically for the aesthetic, to accentuate the beauty of the backyard, or the view beyond the pool.
- Help your students ‘find the art‘ in your pool, and show you the various elements of design and style. Look at the shapes, the curve and slope, and try to determine function from form. Which design elements serve a specific purpose or function, meaning it works better that way, and which seem to have no purpose, other than for style or beauty?
- Have your students create a plan to make the backyard more visually appealing using landscape design, pool design, and outdoor decor. Help and encourage them to first establish a general (or specific) theme, visual focal points and a color palette, and don’t forget outdoor lighting, and stylish pool furniture to really make it pop!
Math in the Pool
And we also have a lot of math around the pool. The engineers, designers and pool builders use a lot of mathematics during design and construction of a swimming pool. And when sizing pool equipment, such as a pool heater, diving board or pool slides, you’re going to need math.
When selecting your pump and filter for example, the total resistance level of the circulation system is calculated, to select equipment that can overcome the resistance effectively, while still meeting the turnover requirement of filtering all the water in the pool, during an 8-hour period.
Math is also involved when testing your pool water. Titration testing, used for Alkalinity, Hardness and Stabilizer tests, are performed by counting the number of titrant drops added, until a color change is observed. And when calculating dosage for adjustment chemicals or treatment chemicals, you will use math to convert to your pool size.
Math Exercise: Have your students compute the number of gallons of water in the pool using the formula below.
Rectangular pools: L x W x Avg. Depth x 7.5
Oval pools: L x W x Avg. Depth x 5.9
Round pools: Dia. x Dia. x Depth x 3.14
Extra Credit – have your students compute the desired GPM flow rate for the pool pump, to meet an 8-hour turnover requirement. In other words, knowing the total amount of gallons in the pool, what flow rate (in gallons per minute) would be required to pump all of the water in the pool through the filter, in an 8-hour period (480 minutes)?
My students (kids) have had all these lessons in our backyard pool. Just ignore the sighs and the eye rolls when you drag them outside to learn about the pool. There’s good learning in the backyard! Real-world knowledge that they can see and touch – even if your pool is still closed for winter.
Oh, and feel free to get some tasks done while learning about the pool (wax-on, wax-off), with this post – “Pool Chores for Children“.
Stay safe and enjoy your pool! In The Swim is proud to provide chemicals, equipment and the specialized knowledge you need, to maintain a healthy pool for your family!
In The Swim Blog Editor