How to Remove Nitrates From Pool Water and How to Prevent Them

The pool industry tries to sell pool nitrate remover to you, but is it really necessary?

Are nitrates in pool water really that bad?

In this post, I explain what nitrates are, where they come from in your pool, how to get rid of them, and why you don’t need an extra nitrate cleaner.

What are nitrates?

Nitrates are naturally occurring chemicals that are found in water and soil.

Nitrates can come from natural processes, agricultural practices, or bad swimming habits. Nitrate pollution can harm ecosystems by promoting excessive plant growth, which chokes out other plants and aquatic life.

Nitrate contamination is a concern for human health because it boosts the formation of potentially cancerous compounds in drinking water and your pool water.

What happens when your pool has nitrates?

In swimming pools, nitrates promote the formation of a chemical irritant called chloramine that causes the familiar strong chlorine odor.

The presence of chloramines in pool water indicates elevated levels of total combined chlorine. Higher concentrations of total combined chlorine can cause irritation to swimmers’ eyes, skin, and respiratory systems.

At what levels are nitrates considered to be a problem?

Nitrate levels exceeding 10 ppm (mg/l) in drinking water or 25 ppm in recreational waters indicate an increased risk of methemoglobinemia for infants under six months old.

Are nitrates and phosphates the same thing in pool water?

Nitrates and phosphates are very closely related and often found together in pool water, making them difficult to separate.

Nitrates are simply a type of nitrogen compound. Many different types of nitrogen-based chemicals can be found in pool water. This includes both organic and inorganic forms and combined or free states.

Nitrate is also known as NO3, nitrite is NO2, nitrogen gas N2.

Phosphates (PO4) are another form of a nitrogen-containing compound found in swimming pool water and are one of the most common forms. The Phosphate test kit sold at the pool store will differentiate between the combined free state and determine whether it is organic or inorganic phosphate.

What causes nitrates in pool water?

Nitrates become dangerous when they get too high in pool water.

But what causes the nitrates in your swimming pool to rise?

  • Nitrogen Cycle: Sometimes, tap water itself can contain nitrates already, or other sources could cause high levels in the pool.
  • Humans: Humans can introduce a lot of nitrate into the pool. This happens when people intentionally urinate in the pool, or other contaminants are introduced.
  • Septic tanks and wells: If your pool is in or near a septic tank, this can be another cause of high nitrates. This happens when the septic system overflows out into the yard or your pool.
  • Rain: Many nitrates are brought into the pool and spa water with rainwater. For example, you can expect around 100 ppm of nitrates when acid rain has made its way into your pool.
  • Animal waste: If you allow your dog or the neighbor’s dog to swim in the pool, then you don’t have to wonder about elevated nitrate levels. The same is true when wild animals swim in the pool and drown in it.

All of these possible causes contaminate your pool and need to be removed from the water.

If you want to lower the nitrate levels in your pool, read how to get rid of them.

How to get rid of nitrates in your swimming pool?

The best way to completely remove nitrates from the pool water would be with thorough pool maintenance.

  1. Run your pool filter daily for about 6 to 8 hours/day.
  2. Scrub your pool regularly with a pool brush and use a pool vacuum to get rid of the dirt on the bottom.
  3. Improve the water filtration with a pool flocculant. Place a flocculant pillow into your skimmer.
  4. If that is not enough, shock your pool to eliminate the bad smell that nitrate produces in the water.
  5. Watch out for the growth of algae blooms. Treat the pool with pool algaecide to prevent further infestations if you see them.
  6. Add a chlorine tablet into your floater or the skimmer to produce free chlorine. This will constantly eliminate the nitrates.

You can also try a special pool nitrate cleaner to see if it removes the nitrates.

Maybe you should also install a UV pool water purifier that kills bacteria, which helps remove bacteria from the swimming pool water and thus reduce the level of nitrates.

How to prevent a high nitrate level in your pool?

The best method against nitrates in your pool is to prevent them.

To avoid the nitrates in your pool, you should not let water sit still. Keep on circulating, filtering, and adding chlorine to it.

Over time this will eliminate all the excess nitrates that build up in the water due to heavy use or nitrate-filled tap water.

Place a shower in front of your pool and force all bathers to shower before entering the pool. This will help a lot to keep the nitrates level low.

If you don’t have room for a backyard shower, at least put a foot bath in front of the pool.

Tip: You should read my pool rules guide. This will help you in the fight against nitrates.

Conclusion on nitrates in swimming pools

Nitrates may be present in either a combined or free state, but there is no easy way for the average consumer to tell the difference.

Nitrates are very common in pool water but are rarely seen as a problem.

Nitrates are generally removed through the pool filter system or chemically removed with commercial products specifically designed for this purpose.

High nitrate levels above 50 ppm will often turn blue litmus paper pink and red litmus paper purple, but this will only work with free nitrates in solution.

This is not a reliable test for determining if your pool has combined or free state nitrates.

Nitrate levels above 50 ppm can also be determined by testing strips, just like you do with chlorine levels. The only difference being the proper reagent needs to be added to the test strip.

Do you have further questions about nitrates in your swimming pool?

The best way to contact me is @contactswimfool on Twitter or Pinterest. I am happy to help you.

Have fun swimming!

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Hi. I'm Max Berg. I've been in the pool industry since 2015 and have always felt drawn to water. I'm the author behind, where I share my years of experience in pool maintenance and give helpful tips on keeping a swimming pool or hot tub clean. My tips reduce the costs of water treatment and protect the environment.

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