7 common swimming pool problems (and how to fix them)

America is home to over ten million private residential pools, and the private pool has been an iconic element of the American Dream for decades – but the realities of pool ownership aren’t purely idyllic.

Owning a pool means keeping it clean, carefully balancing water chemistry, practicing regular pump maintenance, troubleshooting electrical problems, and more. However, as long as you’re willing to put in the work to keep your pool regularly maintained, either yourself or with the help of a weekly pool cleaning service, it will serve you well for years to come – and provide you with loads of fun.

That being said, there are a few swimming pool problems that aren’t as easily fixed with a quick backwash of the filter or a lap around the poolside with the skimmer.

Maybe you’ve been a bit busy these past few weeks and have had to neglect your pool duties. Maybe you’ve had a storm recently, and your pool has suddenly changed color. Or maybe you’ve been discouraged by recurring or major problems like cloudy pool water and troublesome plaster stains.

Don’t worry – we’re here to help. Let’s take a moment to run through the seven most common swimming pool problems, and how to fix them.

1. The pool is turning green

A change in color is one of the most common swimming pool problems homeowners experience. When most of us think of an inviting pool, we don’t think of a swampy mess. We see clear azure waters, off-white plaster, and clean pool tiles.

Unfortunately, it doesn’t take a lot for a pool to start changing color, and most of the time (especially when it’s green), it’s because of a buildup of algae.

Algae is the pool owner’s most common and persistent biological enemy. It’s a class of organisms that is largely plantlike, feeding off of the sun’s UV rays and carbon dioxide. As it grows and multiplies, pool algae become thicker and more slime-like in nature, making your pool water murkier and darker.

Aside from being an eyesore, algae can become a serious threat to your pool if left unchecked. Algae can stain and erode your pool’s surfaces by drastically altering the chemical balance of the water, clog and destroy your filters, and trap harmful bacteria.

To fight a biological enemy like algae, you need the right tool. In most cases, it’s chlorine or a similar pool detergent.

Green water is a sign that you need to use a chlorine shock to reintroduce large amounts of free available chlorine into your pool, then use a combination of rigorous pool brushing and multiple hours of pumping your water through a clean filter to get your pool back to normal. Most chlorine shock products are either sodium hypochlorite (liquid) or calcium hypochlorite (dry).

Related: How to Clean a Green Swimming Pool

2. Dealing with a dirty filter

The filter is like the pool’s liver, and it requires regular maintenance and an occasional transplant when things get really bad. Most dirty filters get clogged over time due to sheer volumes of dead and living organic and inorganic matter, from algae to soil and metal residue.

Make sure to check your filter often and give it a proper hose down whenever its starts to get clogged. Many pool pumps also give you the option of backwashing your filter to clean it out.

You can use your filter’s pressure gauge to determine just how clogged it is – but as a general rule, consider spraying or backwashing your filter about once a week, or at least once a month.

A filter’s ideal water pressure will differ from pump to pump. Be sure to make note of what it was when it was first installed (or last cleaned), versus what it’s like when it starts to get clogged. This way, you can use the pressure gauge to determine how often your filter needs a thorough wash.

3. Identifying and removing calcium buildup

If the surface of your pool (especially at the water level) is starting to form a whitish buildup of grime, you may be dealing with excessive calcium. Calcium deposits are a symptom of a larger swimming pool problem, one you shouldn’t ignore.

Most pool calcium buildup is caused by a chemical imbalance in the water. In many cases, calcium deposits are a sign that your alkalinity (the density of buffer minerals in the water) is too high. If your water pH and alkalinity are off, the calcium in your pool begins to clump and separate from the water.

Excess calcium carbonate is easy to remove with a scale remover or a pumice stone. You can also use a stain eraser to target especially hardy spots. Your exact descaling plan will depend on the build and makeup of your pool – fiberglass pools need a different descaling treatment than concrete pools.

4. Cloudy pool water

Several things could cause pool water to cloud up. These include:

  • High alkalinity.
  • High calcium hardness.
  • A clogged/dirty filter.
  • The aftermath of a storm.
  • Backyard debris.

If it isn’t the filter or the water balance, consider screening your pool in and running the filter again. There might be too many organic and inorganic materials coming into the water for your filtration system to keep up.

5. Pool plaster stains

Pool plaster stains are caused by several things, including fallen fruit or decomposed leaves, metal deposits from eroded soil or corroding pool fixtures (particularly iron), metal levels in well water (especially manganese and copper), fiberglass shells (cobalt buildup), or algae.

Different stain kits can help you identify what kind of stain you’re dealing with, and how best to clean it.

Most organic stains can be cleaned with sprinkled chlorine and a dedicated scrub. Inorganic stains, however, may need to be identified and cleaned with a respective stain cleaner, depending on the cause of the stain.

Stain kits can be found online, or at a nearby pool supplies store.

Related: How to Remove Stains from Pool Plaster

6. Chemical imbalance

Adjusting your water balance is a critical part of solving several different swimming pool problems.

Start by testing your pH and alkalinity. The ideal pool water pH level is around 7.4. The ideal alkalinity for a pool is about 100-150 parts per million (ppm), depending on who you ask.

If your alkalinity is way higher, start by draining your pool, and filling it up with fresh water. A high pH can be brought down with an appropriate pool acid. A gallon per 10,000 gallons of water is a good start. Wait a day and retest.

The third aspect of good pool water balance is your chlorine levels. The recommended chlorine level for a pool is between 1 and 3 ppm. You can raise your chlorine levels with a pool shock, preferably after sundown. High chlorine levels solve themselves through sunlight, or by draining the pool a little and adding fresh water.

6. Cracked pool plaster

If you own a concrete pool, then you’ll eventually need to deal with cracks in the plaster. Properly installed plaster is designed to expand and contract with shifts in the ground – but over time, it loses its plasticity, and fractures begin to occur.

Chemical imbalances in the water can also serve to speed up the rate at which your plaster gets damaged. Small, single cracks can be repaired on a DIY level. Large, net-like cracks require professional attention.

If the damage is still minor, you may be able to do a few repairs on your own. But even DIY plaster repair with a full pool can call for epoxy putty, underwater sealers, and acid. Depending on the extent of the damage, it can be a long process, and not a particularly safe one. If you have no experience with repairing pool plaster, consider calling a professional.


If you’re experiencing any of the swimming pool problems mentioned above and need help, consider contacting PoolSense. Our expert pool technicians handle all aspects of preserving, maintaining, and repairing swimming pools for both residential and commercial customers.

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