What Causes High Phosphates in the Pool? (& What To Do)

After months of not using your pool, you may have noticed some growth in the water. I’ve experienced this before. I hadn’t used my pool for months and summer was around the corner. I went to take a look and the water was green, there was a ton of algae, and I was shocked. 

I realized the growths are caused by phosphates. Phosphates are completely normal but need to be maintained. They grow when natural substances enter your pool such as soil or leaves. From then on I have my pool cleaned regularly. You should try to avoid the growth of phosphates in your pool by keeping it clean or with the use of a pool cover.

High phosphate levels in your pool will cause it to turn green or have algae growth. Common causes of high phosphate levels are garden products, city water, trees, pool chemicals, swimmers, detergents, and garden litter. Easy ways to keep the phosphate level low are to clean your pool or use products that rid of phosphates.

What is phosphate & Why is It Important 

Phosphates are organic chemicals that naturally occur in your pool. They are derived from phosphoric acid. They come from natural sources such as trees or garden products. Phosphates feed algae and over time if not cleaned, help the algae grow in your pool. 

It is impossible to completely get rid of phosphates from your pool. There will always be a small amount lingering around. However, you should not worry about a low amount of phosphate in your pool. All you have to do is keep your pool clean and it will not have any phosphate buildup.

You shouldn’t be scared of phosphate either. Phosphates are essential to all life. They play a huge role in the formation of DNA. Along with being necessary for the structure of bones and teeth. In fact, phosphates are in the food that we eat. We just don’t want an excessive level of phosphate in our pools.

Different Levels of Phosphates 

What Is Acceptable level? 

An acceptable level of phosphates in your pool is anywhere between 100-125 ppm (part-per-million). This is a low level of phosphates and will not cause any harm to you or the water in your pool. Generally, you do not want any phosphates in your pool if possible. 

Phosphates will constantly enter your pool. Every day and every night phosphates will continue to break off into your pool. This is because the natural elements will get into your pool. If you have an indoor pool you will still get phosphates in your pool because they come from people as well.

It is impossible to get rid of all of the phosphates in your pool. Keep the levels low by cleaning them every week. If you can’t clean it every week you should hire someone to come by and take care of your pool. They can easily and safely shock your pool so you can enjoy it again.

What Are Dangerous Levels?

The dangerous levels of phosphates in your pool are anything that is 500 ppm and above. This is when algae start to grow and the pool water turns green. Although phosphates may be a naturally occurring substance that is normally not dangerous, too much can be harmful.

Dangerous levels of phosphate levels will cause algae to grow more. The more algae mean that it will be harder for you to clean your pool. If it is hard for you to clean your pool then you will have to pay a lot more. The dangerous levels of phosphates can also use the chlorine up quickly. This will cause you to have to pay more for chlorine.

If you notice that your pool is green, do not jump into it, and try to not touch the pool. Getting too much phosphate in your body can cause underlying diseases. If you have kids or pets keep them away from the pool as well. Although the danger is not immediate and you would likely be okay if you went into the pool it is best to stay safe.

Causes of high phosphates

1. Garden products

Garden products can cause high phosphates in your pool over time. Check to see if you have any garden areas close to your pool or have any sort of plants around the pool. It is likely the garden products are entering the pool. These products can be blown by the wind and brought in by outside animals.

2. City water

City water has a lot of minerals and potentially can contain bacteria. City water can get into the pool and is properly what you fill your pool up with. Chlorine is supposed to combat bacteria and unwanted minerals in the pool. Chlorine should combat the minerals in city water. 

Another way that city water can get into your pool is by filling your pool up with a hose. If there was a lot of rain the city water could drain off into the pool. Generally, chlorine should be enough to combat city water but if your pool lacks chlorine it will not.

3. Trees

Trees are constantly shedding leaves or branches that have dried up. Phosphates will come off of these dried-up or dead plant leaves. For example, the wind will blow the leaves into your pool and the phosphates will enter your pool.

This is not just exclusive to trees. Any plant life that gets into your pool will give off phosphates. Over time the build-up will be too much and cause the pool to turn green and grow algae. 

4. Pool chemicals

There are certain pool chemicals such as scale and stain inhibitors that contain phosphates. If you are using these in your pool you should measure the level of phosphates after use. This way you can see if adding those cause the phosphate level to be too high. If so, you should add phosphate remover to combat the phosphates in those products.

5. Swimmers themselves

Swimmers can bring in phosphates to your pool. People build up bacteria and other natural chemicals as they go on with their day. The phosphate level will rise if you are having a bunch of friends over for a pool party or swimming in your pool regularly. Remember to wash off before jumping in.

6. Detergents

Detergents can cause phosphates. Residue from detergents comes off on swimmers from their clothing or the use of a towel. Their bathing suit may contain detergent residue as well. Swimmers should try to rinse off before entering the pool.

7. Garden litter

Leftovers from a garden also known as garden litter can get into your pool. Just like dead plant leaves or branches, garden litter can be blown into the pool by the wind. Phosphate levels will rise from this.

How do phosphates promote algae growth?

Food for algae

Phosphates are food for algae. The algae take in the phosphates and multiply until your pool is a soup of algae. Nitrogen is another food for algae. A combination of nitrogen and algae will allow for algae to thrive. Dead algae can benefit from phosphates as well.

Snowball effect of dead algae

Dead algae can come back to life. It does this by letting off spores. These spores will then grow in your pool with the help of phosphates and nitrogen. Since the dead algae let off spores the algae will continue to overtake your whole pool. These spores will forever duplicate until you clean the pool.

Like most organisms the goal is survival. Algae may only be a plant but if it has the opportunity to continue to grow it will. If you do not clean your pool then the algae will take the opportunity you have given it to grow. 

Unfortunately, an excess amount of these spores are dangerous. You should stay away from your pool if you see that there is a ton of algae in it. Hire a professional to clean the pool so it can be properly taken care of.

What Can Be Done To Reduce Phosphates In Your Pool

Regular testing

Test your pool’s phosphate level regularly. To test for phosphate levels get a phosphate testing kit. If you keep your pool clean you will not need to worry about the phosphate level that much. 

Cleaning pool

Cleaning your pool regularly will keep phosphate levels low and help maintain your pool’s overall health. Meaning that algae will not grow. You should hire a pool cleaner that comes on a regular basis. Along with hiring a pool cleaner, you should do some small maintenance. Cut back brush around your pool and net out leaves every other day.

They will use pool cleaning tools to clean the pool. They use a net to get rid of leaves or anything floating. Then they will use special equipment to clean the tiles and bottom of the pool. The special equipment is a pool cleaner vacuum and it will scarp off any type of build-up.

If your pool already has algae growth then you will need to hire someone to clean the algae out. They will use a ton of phosphate remover and chemicals to clean the algae. They will clean the sides of the pool and net out anything else. It is possible that you may just have to drain your pool.

Products to remove phosphates

There are plenty of products that remove and reduce phosphates from your pool. Such products include, but are not limited to:

1. Seachem PhosGard

2. Natural Chemistry Phosfree

3. HTH Phosphate Remover

4. Orenda Phosphate Remover Concentrate

5. SpaGaurd Phosphate Remover

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