What Makes Your Pool Green?

As a pool owner, there’s nothing worse than looking out at your pool and seeing green water. It can happen even to experienced pool owners, but it’s easily reversible once you know what caused the issue in the first place.

The pHin experts put together a list of reasons why pool water goes green:

#1 Not Enough Chlorine

Chlorine is important for sanitizing water from bacteria and other contaminants. Lack of chlorine is one of the most common causes of green pools. If the pool water is not balanced with proper chlorine levels, algae will start to grow, causing the water to turn green. The growth of algae also speeds up as warmer weather arrives so a regular pool care routine can keep it in check.

#2 The Weather

Depending on where you live, the weather can have an impact on your pool water clarity. When pollen levels are high, the water may turn green more frequently. Pollen is too small to be properly managed by the pool filter and it might require cleaning with a brush or skimmer. For those who live in hot and humid climates where algae thrives, a higher amount of chlorine can help prevent potential algae buildup.

#3 Unbalanced pH

pH measures the acidity of your pool water, and can fluctuate due to weather, temperature, and pool use. If the pH of the water is too high, chlorine becomes less effective, which can allow algae to grow in the water.  Monitoring your pH levels, along with a regular pool care routine, can help prevent an environment where algae can grow.

#4 Pool Pumps and Filters

If your pump or filter is too small for the size of your pool, the system can’t properly filter and get rid of algae and other debris that enter the pool. Or even the right size pump can’t effectively clear the water if it’s not running regularly. Check with your pool manufacturer for the right size and run time required for your pool to keep it safe.

Keeping an eye on your pool water conditions and equipment can prevent a cloudy green pool. pHin can help by reporting whether your pH levels need attention. It takes over 1,000 measurements a week,and will alert you through your smartphone app if your water’s pH is off. When there’s a problem, you’re not on your own – pHin also helps out by providing chemical dosing instructions to right the imbalance before the water gets off track.

Learn more about pHin here.

What Makes a Pool Green?

Have you ever left your pool looking pristine, only to wake up finding that it’s turned green virtually overnight? If so, you are absolutely not alone and it’s also worth noting that your pool turning green can be reversed with some diligence. The most effective way to clear a green pool is to first diagnose the source of the problem.


While the most common cause of a green swimming pool is algae, it’s not the only cause for the change in color. A few other culprits range from improper pH or Cyanuric acid (CYA) balance, to lack of chlorine, undersized filters, and even weather in some cases!



As stated, the most common reason pools turn green is due to algae growth, which is caused by a lack of chlorine. Chlorine is typically the most common chemical used to sanitize the water from bacteria and other contaminants. The longer your pool remains under-chlorinated, the more algae grows.



pH is the measure of your pool’s acidity. It fluctuates based on factors like oils, dirt, and weather, but should always remain between 7.2-7.8 in order to be considered healthy. A pH balance below 7.2 indicates high acidity that can lead to the erosion of your pool’s plastic and metal parts. When your pH is too high, your chlorine can be rendered ineffective and won’t eliminate bacteria. Instead, you may find buildup of minerals like calcium.



Cyanuric Acid can act as a reservoir for free chlorine (FC), so it’s important to make sure that you maintain a healthy ratio of the two chemicals in order to keep from growing algae and turning green. Some recommend that your FC should be 7.5% of your CYA level.



To determine whether or not an undersized pump/filter is causing discoloration, verify how many gallons of water your pool holds and calculate whether or not you’ve chosen the appropriate size based upon the shape of your pool. Having a filter that is too small leads to more maintenance work, which is why it’s widely recommended to oversize by a little bit.



Heat and humidity are the perfect breeding grounds for algae growth and may hinder the effectiveness of your chlorine treatments. If you live in a climate that produces a lot of heat and humidity, consider using specialty chlorine and algae remover.



Figuring out the culprit behind what makes your pool green is a lot of work when you don’t have the right technology. The pHin smart monitor audits your pool’s water quality 24/7, notifies you when it’s time to add chemicals, and ships you exactly what you need, in pre-measured doses. Just drop in the color-coded pod and enjoy clean, perfectly balanced pool water all season long. You also have the option to call on a nearby pool tech through the app if ever you need professional help maintaining your water.

Rio Olympic Swimming Pools Turn Green – We Know Why!

In Rio, the show must go on. Olympic officials tested the water with traditional methods and deemed it safe for competition – a smart pool solution, like pHin, might have saved them a headache. Though safe for swimmers, the sight was no doubt unsettling for athletes as they plunged into the murky green water.

While the adjoining pool used for water polo and synchronized swimming held its blue hue yesterday, that pool is now giving way to the algae as well.

“This just goes to show that even though the water’s crystal clear, some invisible issues like algae can rear their ugly head overnight,” said pHin pool chemist Christian Ballard. “Algae is typically undetectable to the human eye until the algae spore content reaches approximately 30,000,000 spores in one ounce of water!”

Heat and lack of wind were to blame in this instance, but a properly balanced pool is much less susceptible to algae blooms. With pHin, The Smart Pool Solution officials could have kept their pools perfectly balanced, sat back and enjoyed the competition.