Pool Care 101: Circulation, Cleaning, and Chemistry

Pool Care Chapters

Pool Maintenance Schedule

Maintenance TaskDailyWeeklyMonthly
Check water level1x
Check pump basket1x
Pool shock1x
Treat for algae1x
Vacuum and brush1x
Test and correct chemical balance1x
Skim pool surface2x
Treat for algae1x
Vacuum and brush1x
Test and correct chemical balance1x
Clean and filter1x

Pool care begins and ends with circulation, cleaning, and chemistry. For the most part, the pool pumps determine the circulation. Most of the cleaning comes down to human effort. Chemistry is either all human effort or a combination of human effort and an automated sanitation system. 

This article will give a brief overview of these three aspects of pool care and include quick reference charts and links to articles where it is deemed useful. 

Circulation (and Filtration)

The circulatory system of your pool works like the circulatory system of any animal. The pool pump is the heart, and the pressure it generates pushes the water through the pipes. The circulation disseminates both chemicals and heat throughout the pool, and the pool’s filtration system is built into it and will not function without it.

To achieve and maintain proper circulation, you will need to do the following:

  • Cycle the pool water through the filter at least once per day
  • Clean the pool filter when the pool pump’s PSI meter increases by 10
  • Clean the skimmer and pump basket, somewhere between once per day to once per week
  • Synchronize the orientation of the water jets to create a downward spiral

There are four critical elements to pool circulation and filtration systems that we would like to discuss:

  • Pool Pumps
  • The filtration system needs to be clean
  • Is the skimmer clean?
  • Proper orientation of return jets

Pool Pump

The pool pump is the heart of your pool. It keeps the water moving and pushes the water through the heater and filtration system. There are two important attributes to every pool pump:

Flow Rate: If the pool pump is the heart of your pool, its pulse is the flow rate. The flow rate is the measurement of how many Gallons Per Minute (GPM) or Gallons Per Hour (GPH) a pool pump can achieve.  

Turnover Rate: The turnover rate is the measurement of how long it takes all of the water in your pool to cycle through the pool pump a single time. Average day-to-day maintenance only requires a single cycle each day, but you should purchase a pool pump that can achieve an 8-hour turnover rate.

When you have determined the turnover rate you want to achieve, you can use the chart below to find the flow rate you will need. 

If you want to know the differences between these turnover rates and their benefits or want answers to common questions, you might want to visit our “Pool Pump Size Calculator” guide.

Here's how many GPMs are required to achieve specific turnover rates

How many gallons are in your pool?6-Hour Turnover8-Hour Turnover10-Hour Turnover
10,00028 GPM21 GPM17 GPM
15,00042 GPM31 GPM25 GPM
20,00056 GPM42 GPM33 GPM
25,00069 GPM52 GPM42 GPM
30,00083 GPM63 GPM50 GPM
40,000111 GPM83 GPM67 GPM
50,000139 GPM104 GPM83 GPM

Cleaning and Backwashing Filters

Frequency: Typically, filters will need to be cleaned once every six months. It needs to be done whenever the pool pump climbs by 10 PSI.

Write down your pool pump’s PSI when you install a new filter. That PSI is a baseline you need to know that will help you determine when your filters need to be cleaned or backwashed. The general recommendation is to clean or backwash the filters once the pool pump’s PSI has climbed by ten from that baseline.

Useful Note about Sand Filters

Sand filters’ filtration improves as it becomes clogged with filth. The goopy mess that has been filtered into the sand acts as another layer to the filtration. As long as the PSI hasn’t increased by 15+ PSI, we recommend taking advantage of that increased filtration and vacuuming the pool before backwashing the filter.

Clean the Skimmer Basket and Pool Pump Basket

Before water goes through the filters, it first needs to go through the skimmer and pool pump baskets. These baskets capture the large debris and leave the small debris for the filters. 

These baskets can clog up quickly and will need to be cleaned out between once per day and once per week. How often you need to clean these baskets will differ depending upon factors such as local flora and fauna, the current season, how many people use the pool, and how often they use it.

We already have a detailed guide on “How to Clean the Pool Pump & Skimmer Basket,” so you can head there if you would like a thorough explanation.

Orient the Water Jets to Promote Circulation

We need the water to circulate. If the direction of one water jet opposes another, much of the water’s momentum will cancel out.

How to Balance Your Pool Chemicals

The purpose of pool chemicals is to protect the equipment, pool, and swimmers from threats such as algae, bacteria, and corrosion. 

Healthy pools are maintained through a daisy chain of chemicals. Each of the chemicals requires the other, and all of them must be kept within their associated ranges that we’ve listed in the chart below. When one chemical is out of range, it disables, hinders, or eliminates the other chemicals. 

Additionally, pool chemicals should be added in a specific order to prevent wasted time and chemicals. As the chemicals interact, the ratios change, and the chemical doses become more difficult to calculate. If you stick to the recommended order that we have listed below this paragraph, the chemical balance should not fluctuate in unexpected directions after you add each chemical.

Add Pool Chemicals in The Following Order

  • Total Alkalinity
  • pH
  • Calcium Hardness
  • Stabilizer
  • Sanitizer

Adjust Pool Chemicals to Be within the Following Ranges

Ideal Chemical Ranges

Chemical NameIdeal Range
Alkalinity80 to 120 PPM
Calcium Hardness
200 to 275 PPM
Calcium Hardness
(Fiberglass and Vinyl)
175 to 225 PPM
pH7.2 to 7.4 PPM
Cyanuric Acid30 to 50 PPM
Chlorine1 to 3 PPM

What Does Each Pool Chemical Do?

Each chemical has a role to fulfill, and some of them just keep the other chemicals from screwing everything up. In this section, we will describe the most important chemicals/aspects associated with pool care. They are alkalinity, calcium hardness, chlorine, cyanuric acid, and pH.


Pool water needs to be acidic enough to convert the pool’s chlorine into hydrochloric acid and enough hydrochloric acid to dissolve any calcium that’s trying to solidify itself as calcium scaling. 

However, we need to be careful not to make it too acidic. Otherwise, it starts to become dangerous to people and the pool walls.

Acids are sometimes called “proton donators,” and those donated protons are hydrogens. Chlorine requires hydrogen to form hydrochloric acid, and hydrochloric acid is used to sanitize the water. To state it another way, the chlorine will be ineffective without a pH low enough to provide sufficient hydrogens to create hydrochloric acid.

To bring your pool’s pH within the ideal range, we need a way to measure the acidity of the water. We call that measurement its pH, and pH stands for “potential hydrogen.”

Contrary to what we would naturally expect, the concentration of proton donators (hydrogen donators) goes up as the pH number goes down. It’s weird, but that’s how we measure it.

To use an example, a pH of 3 is more acidic than a pH of 4.

Please take note that we measure pH ratings on a logarithmic scale. That means that each number is 10x more acidic or 1/10th as acidic as the number next to it. For example, a 3 is ten times more acidic than a 4. If the 3 were a 2, it would be one hundred times more acidic than the 4.

Chlorine (Sanitizer)

As the sanitizer, chlorine is the star of the show. Sanitizers kill and mutate algae, bacteria, and viruses that infiltrate your pool water. If nothing is done, the bacteria and viruses will multiply, invade swimmers’ bodies, multiply some more, and make the swimmers very sick. In extreme cases, these unsanitary could even have lethal consequences.

There are several types of sanitizer, but chlorine is the popular choice. Chlorine comes in three primary forms: liquid, granules, and tablets.

Types of Chlorine

Liquid Chlorine vs. Bleach

The liquid form of chlorine is not concentrated. When adding chlorine, give special attention to the concentration of the sanitizing molecule called sodium hypochlorite (NaClO). The more sodium hypochlorite you have, the more powerful the sanitization. 

If you buy liquid chlorine, the sodium hypochlorite concentration will generally be around 12.5%. You can also use ordinary household bleach, which will usually have about 8% of sodium hypochlorite.


Granules have a sodium hypochlorite concentration of 50 to 70%. That makes it a popular option when performing a pool shock.


Tablets have an extremely high sodium hypochlorite concentration of roughly 90%. Tablets are a slow-releasing form meant to maintain chlorine levels for a period of 3 to 7 days. 

Cyanuric Acid (Stabilizer)

Chlorine evaporates quickly. Without intervention, it only takes minutes to hours for the majority of a fresh batch of chlorine to leave your pool. How fast this happens depends upon the intensity and directness of the sunlight.

A stabilizer, such as cyanuric acid, binds to the chlorine and prevents it from leaving the pool water. That said, you need to be careful not to add more cyanuric acid than is needed. We need chlorine to bind to contaminants. If there is too much stabilizer, the chlorine will be too busy binding to the stabilizer to effectively cleanse the pool.


If no measures are taken, pH values can spike and change. Alkalinity brings stability to the pH value by increasing the water’s capacity to resist acidification.

We raise alkalinity by adding a buffer solution to the water. Buffer solutions hold the pH steady by switching between acid or a base depending upon the chemical pressures within the water.

Buffer solutions form in one way that presents themselves in two forms. In the first form, you can have a mixture of a strong acid and its conjugate base. In the second form, there is a strong base with a conjugate acid.

Calcium Hardness

Calcium hardness is a common problem where water, heat, and piping intersect. Most molecules become more soluble as the temperature increases. Calcium bucks this trend and becomes less soluble in warm temperatures. This is a notable characteristic because it indicates where you can expect to find calcium buildup; usually called calcium scaling.

When Is Calcium Hardness a Problem?

Calcium scaling usually happens in two environments. First, when the pH value is too high, the water isn’t acidic enough to dissolve the calcium. Without an acidic opponent, the calcium will be free to build on the pool surfaces.

Before we get to the second calcium scaling environment, we need to give a quick chemistry refresher. Some compounds are water-soluble, and some are fat-soluble. All of them have solubility limits. When a compound’s concentration exceeds its solubility limits, anything beyond that limit is insoluble. 

With all of that said, we can now say that the second calcium scaling environment occurs when the calcium concentration within the water exceeds the calcium’s solubility. Any insoluble calcium will form into scaling on exposed surfaces or float freely and cause the pool to become cloudy.


Nature has a strong habit of seeking entropy and balancing pressures whether it is chemical, electrical, heat, or your classic air pressure. In the case of calcium, water seeks to balance out something we call the Langelier Saturation Index (LSI). 

The LSI is how we measure a calcium’s tendency to scale vs. dissolve. Water naturally wants to bring this scale to a 0.

The LSI is another balancing act, but going into it here would take us off-topic. Instead, we’ll just say to keep the pH and Alkalinity in the “Balanced Zone” of the chart below this paragraph. 

The LSI is a whole topic that deserves a guide. That’s why we wrote one (our guide to calcium scaling). The guide goes into all the LSI factors: alkalinity, calcium, pH, stabilizer, temperature, and total dissolved solids. If your having trouble with scaling, definitely read the guide. Otherwise, this chart can give you a rough idea of how you can expect the calcium to behave.

Questions and Answers

What to Do When You First Fill Your Pool?

A freshly filled pool can face a whole host of potential problems. City water is focused on filtering contaminants that pose a danger to humans but not pools. White water mold, hard water, low pH, and several other issues can cause immediate problems for your pool. For that reason, your first concern should be to fix the water. Test the water, adjust the chemical balance, set the filter to “filter”, and turn the pool pump to “on.” After all of that is done, plan your maintenance schedule.

Should You Shock a Newly Filled Pool?

Yes, your pool doesn’t have issues yet, but adding more water is one of the most common ways that problems can be introduced. A pool shock is a great way to start your pool water off with a clean slate. 

How Soon After Filling a Pool Can You Swim?

If it’s safe to drink, it is safe to swim. However, problems not dealt with today will become bigger problems tomorrow. Any algae spores, white water mold, or chemical balance issues can cause problems if you don’t do anything about them. For that reason, we recommend shocking your pool and setting up the chemicals first.

Is It Easy to Maintain My Own Pool?

Physical capabilities differ from person to person. However, if you are able-bodied, maintaining a pool is requires more time than effort. Removing algae tends to be one of the most physically intensive tasks, and that just requires chlorine and a scrub brush. 

The Pool Care Handbook & Video Course

by Swim University
This is an illustrated e-book with detailed videos and step-by-step instructions on how to best care for your swimming pool. 
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