Three Early Indicators that Algae is Blooming in the Pool

Swim season provides endless fun and memories, but one thing that can bring swim time to a screeching halt is algae. Algae is a single-celled plant form that uses photosynthesis to manufacture its own food. Algae is microscopic, so by the time it becomes visible on a pool’s surface or in the water, it’s because millions of these plants have accumulated.

Algae is a common issue in swimming pools, especially in the summer as it can reproduce faster in hot weather and requires more maintenance to keep it at bay. It’s important that all pool owners know what causes algae blooms, how to prevent it, and what to do about it when they rear their ugly head.

What Causes Algae Blooms?

Algae growth can be attributed to many things. Heavy pool usage, inclement weather, plant nutrients, and poor water filtration or circulation can all lead to the development of algae in the pool water:

  • Heavy Pool Use: After a pool party, for example, the pool’s chlorine levels may decrease due to the sheer number of bodies in the water, which can leave behind dirt, bacteria and sunscreen. As the chlorine works to eliminate these things, chlorine levels can decrease enough to give algae an opportunity to blossom.
  • Inclement weather: The impact of summer rain and wind storms, along with the heat itself, can serve as a breeding ground for algae in the pool water.
  • Foliage: While plants and foliage around the pool add to the ambiance of an outdoor oasis, their leaves and other organic droppings can actually provide nourishment for algae if left in the pool once they fall in. This is why it’s important to sweep debris out of the pool regularly.
  • Poor water filtration/circulation: Stagnant water is practically an invitation for algae, so proper filtration and circulation are important for keeping algae at bay.


Consistent and careful pool maintenance is the best way to prevent any type of pool algae, but this can be particularly difficult during the hot summer months as temperatures rise. It’s important to keep the pool’s sanitation levels balanced all season long to keep algae from becoming a summer bummer!

The professionals at Aquaman Pools are highly skilled at preventing algae from forming or catching it early before it really takes a toll on the pool water. They also have the equipment and chemicals needed to bring a pool back to its pre-algae crystal clean state — so don’t hesitate to give them a call for algae issues or any pool service needs!

Types of Pool Algae

Not all algae are created equal, and it can show itself in many ways. If the pool water becomes cloudy, that can be a sign of algae growth. A greenish hue to the water is almost certainly a sign of algae, but algae can also develop in patches around the pool. Algae can even show up as dark or black spots that appear to be stains on the pool’s interior surface.

There are three main types of algae that generally impact pool water: green, black and mustard.

Green Algae

Green algae is most often found in pool water. It can cling to the walls of the pool or float in patches atop the water’s surface, which tends to turn the water a greenish hue. This type of algae grows fairly quickly and it can be tough to remove it from pool walls, but generally it is fairly easy to get rid of. Typically a homeowner can fend off green algae by brushing the pool walls and surfaces, shocking the water and treating it with algaecide.

Black Algae

Another common type of algae that can crop up in swimming pools is black algae, which despite its name can appear as a bluish-green shade along cracks in the pool walls. It can appear as spots or stains on the pool, and often forms in areas of the pool that receive the most shade. It requires aggressive brushing to get rid of it as well as the use of algaecide. It’s important to keep a close eye out for this type of algae as it is very hard to get rid of and will likely require the assistance of a professional pool service to take care of it.

Mustard Algae

Finally, there’s mustard algae, a form of green algae that’s resistant to chlorine. It may appear at first to be dirt or sand, but it has a slick and slimy feel. It generally accumulates near pool stairs, lights or ladders or it can settle at the bottom of the pool. It should be treated the same way as black algae.

How to Catch Pool Algae Early

Algae is easier to get rid of the earlier it’s detected. Once algae starts to grow, it can bloom quickly and take some time to rebalance the state of the water.

The longer that algae has to make itself at home and spread, the more trouble it can cause … even to the point of damaging expensive pool equipment. Early detection is key to getting a handle on it before it gets out of hand. But how? Before the whole pool goes green or black spots start dotting the interior surface of the pool, here are some early indicators that algae is starting to grow.

High pH Levels

There are multiple reasons why high pH levels can be a sign of, or a breeding ground for, algae. Typically, high pH levels indicate that the overall chemical balance of the pool is off in some way, which is inviting for algae. Algae also prefers water with higher pH levels.

It’s also important to realize that chlorine is less effective in water with high pH levels. Chlorine is an important chemical in keeping algae at bay, so an environment in which it is less effective can give algae an opportunity to bloom.

Still Water

Is the pump or vacuum off? Better check to make sure those are working because a key part of the pool water’s health is well-circulated water. Still water is most certainly inviting for algae. So if the water hasn’t been moving around at all, it’s time to mix it up before algae starts growing!

Proper circulation is vital for a healthy, algae-free pool. Part of this is because circulation helps distribute pool chemicals throughout the pool. Running the vacuum also sucks up dirt and debris that could house algae. Ideally the pump should be run for at least six to eight hours every day. Keeping the pool water moving and free of debris that could become a host for algae is key. Skimming the surface and brushing the tiles and interior surface of the pool can also help not only keep water moving but prevent algae from collecting.

Cloudy Water

If the pool water starts to become cloudy, milky, foamy or slippery, it’s almost always an early indication that algae is starting to grow. If water goes from crystal clear to cloudy or the sides of the pool feel slippery to the touch, algae might have found a home there!

Aquaman Pools Can Get Your Pool Clean Again

If a pool owner suspects algae is starting to grow, it’s important to take quick action. A pool service company, such as Aquaman Pools, should be highly skilled in treating the problem and returning the water to its clean, clear and healthy state.

Algae is typically one of the most common swimming pool problems and generally it can be taken care of without too much hassle — especially if it is detected and treated early. So keep a keen eye on the status of the pool to nip algae in the bud.