What To Do If Your Swimming Pool Has Nitrates

Nitrates are a common problem for pool owners everywhere. Depending on what part of the world you call home, the problem could be worse or almost non-existent. Still, it is important to always be aware of the nitrate levels in your pool so you don’t have to worry about contaminated water that could become the perfect place for algae to call home.

The key to nitrate control is regular testing, but if you do notice your nitrate levels beginning to rise, it is important to know what to do about it.

In order for you to do that, you need to understand what nitrates are and how they contaminate your pool. Once you understand that, you can begin the process of removing the nitrates and protecting your pool from further contamination.

What Are Nitrates?

Nitrates are a naturally occurring contaminant to pools, much like phosphates.

Nitrates are a plant nutrient and can be found anywhere plants grow and they are also found in man-made fertilizers. So, if you have beautiful foliage surrounding your pool that you have fed with fertilizer, you have created your own source of nitrates that are primed and ready to contaminate your pool.

There are two main forms that are a problem for pools: nitrites (NO2) and nitrates (NO3).

While nitrates are responsible for most the problems pool owners can see, nitrites can be just as much to blame because it isn’t difficult for them to add another molecule of oxygen when they are present in a big huge pool of H20. On top of that, nitrates are much more stable and more difficult to eradicate if your pool becomes contaminated.

Where Do Nitrates Come From?

Where the source of your nitrate contamination is largely depends on the area you live. In rural areas, for example, they most likely come from water run off across foliage. Septic tanks and wells are also known to contain a high amount of nitrates which could run off into your pool as well.

In other areas, simple run off from trees into your pool can cause a contamination. Even basic acid rain can contaminate your pool with nitrates if it isn’t covered during the storm.

Local wildlife and even our pets can also contaminate pools with nitrates. Ducks and other birds are particularly bothersome as they will land in a pool and spend some time contaminating it with their feces and general uncleanness.

Your family dog may love to take a flying leap into the pool, but they are almost as bad as birds. Nitrates from grass and other plant life could be attached to their coats that will wash off into the pool as they swim.

Humans also do their part to contaminate a pool with nitrates. Human sweat and other waste from our bodies combined with cosmetic products can add small amounts of nitrates to your pool. Over time, these levels can build up until you have enough present to allow for quick growth of algae.

What Happens When Your Pool Has Nitrates?

Nitrates in your water won’t cause you any problems directly if you happen to swim it, but in time it can indirectly affect the quality of water.

You see, because they are a plant nutrient, they encourage the growth of algae in your pool. This algae growth can attach itself to the sides of your pool and, of course, turn your water that ugly green color, and who wants to swim in that?

On top of that, if your nitrate levels are high, you will begin to go through much more chlorine in order to keep the pool clean, causing your maintenance costs to potentially skyrocket.

If your nitrate levels begin to get out of hand, rising somewhere in the neighborhood of 10ppm, algae will grow despite your efforts to clean the pool using shock If you click this link and make a purchase, we earn a commission at no additional cost to you. and even algaecide If you click this link and make a purchase, we earn a commission at no additional cost to you. .

How Do You Get Rid of Nitrates?

All that sounds pretty bad doesn’t it? The worst part about nitrates is they are difficult to remove.

If you shock your pool, the existing nitrates will be broken down into nitrites but these can easily convert back to nitrates once your shock levels return to normal, meaning your problem will only continue.

Unfortunately, there is currently no man-made chemical that you can use to solve your nitrate problem once and for all. Your best solution is to first find and eliminate the source of your nitrates, if possible, and then you will need to drain either a portion of the water or all of the water and refill it from a water source that is free from nitrates.

Remember to check the most likely sources such as fertilizers and run offs first. If you are having a pest problem from birds and ducks, there are products you can use to discourage them from choosing your pool as a temporary bath. Diligence is the key.

Test your water regularly and monitor run off sources for your pool. If you notice your nitrate levels starting to climb, don’t waste time before doing something about it. The longer you wait, the more difficult removal will be.


Nitrates are a naturally occurring contaminant that you will have to deal with at some time or another if you own a pool. While they are difficult to eliminate entirely, with just a little diligence and elbow grease, you can keep the nitrate levels in check so you don’t have to worry about algae ever again.

Happy Swimming!

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