The Truth About Using Ascorbic Acid in Your Pool

Your pool water has turned green, and you got the tip in forums to use ascorbic acid (vitamin C) in the pool to remove the cloudiness?

But does that make sense from the point of view of pool experts, and is ascorbic acid actually a miracle cure, as it is often advertised on other blogs?

Ascorbic acid converts the visible trivalent iron hydroxide into an invisible bivalent iron hydroxide and only creates a clear visual effect in green pool water. In addition, ascorbic acid promotes algae growth and neutralizes the disinfecting effect of chlorine.

In this article, I give you two reasons why you should not use ascorbic acid in the pool and which means are the better alternative.

The ascorbic acid only provides an optical effect in the pool

The main reason why I advise against the use of vitamin C in the pool against green pool water is that only a visual clear effect is achieved.

If ascorbic acid is mixed into your pool water, the agent simply makes the visible cloudiness in the pool invisible. This happens because the trivalent iron hydroxide (iron III oxide) is converted into a divalent iron hydroxide (iron II oxide).

The cloudiness in your pool is still present, but it is no longer visible to the human eye.

In theory, you continue to bathe in green and dirty pool water without even realizing it.

Also, if you clean your pool with a pool vacuum and the skimmer, the water will remain dirty.

And as we all know, swallowing dirty water can make you sick quickly.

Therefore, you should not see ascorbic acid in your pool as a permanent solution for pool cleaning. I recommend the right articles for cleaning pool water in my blog.

I have described further problems that arise when ascorbic acid is continuously used in the pool below in the text.

Ascorbic acid neutralizes chlorine in the pool

Suppose you are using a disinfectant such as active oxygen or chlorine in your swimming pool, and the water has turned green.

Then why not use the ascorbic acid powder – in addition to the chlorine – to purify the green pool water?

After all, the pool water became cloudy despite the chlorine?

Would the ascorbic acid in your pool then lead to the desired cleaning result?

First, I have to make one thing clear: The pool water has not become cloudy because you are using chlorine, but rather because you have most likely incorrectly dosed the chlorine and the filter run times of the pool pump are less than 8 hours/day.

If you still use ascorbic acid in the pool, then the disinfecting effect of the chlorine is completely lost.

And what happens if there is no disinfectant in your swimming pool?

Right. The water gets even dirtier, and the cloudiness can only be removed with more pool chemicals. These, in turn, are unnecessary costs for pool maintenance.

Conclusion: The ascorbic acid (vitamin C powder) is cheap in the pharmacy, in DM, or in the Rossmann drugstore, but in the long run, you will have more costs for the necessary water treatment.

You can read in the next chapter which problems arise from ascorbic acid in the pool.

Other problems from using ascorbic acid in the pool

Other problems that result from the optical cleaning of pool water with ascorbic acid are the following:

  • After the second or third use, the pool water will not be clear but rather milky-cloudy.
  • As soon as the pool pump stops running, the water will suddenly turn brown-green again.
  • If the water in the pool is only cleaned with ascorbic acid in the long term, more and more turbid substances will collect in your pool, and the algae will continue to grow.
  • The clearly cloudy and slightly viscous pool water will form a putrid smell that can be harmful to your health.

One point to keep in mind is that vitamin C is an acid.

It is well known that any acid entry in the pool lowers the pH level, and if the pH level falls below 7.0, then in addition to the already mentioned cloudiness of the pool water, damage to the pool and pool equipment also occurs.

The use of acids can therefore be harmful to joints, especially in concrete pools – repairing the joints quickly costs a few thousand euros.

How much ascorbic acid to put in the pool?

You now know the complete truth about pool ascorbic acid, and I have advised you not to use it.

But maybe you have planned a pool party, and the water suddenly gets dirty in your pool.

Nobody wants to swim in green pool water, and a treat with pool shock is out of the question at such short notice.

You can use ascorbic acid in the pool as a last resort and as an exception.

How much ascorbic acid can you then pour into your swimming pool?

The rule of thumb says: For every 1 m3 of water in the pool, 100 g of ascorbic acid (vitamin C) are used.

Then the filter system has to go through so that the agent mixes well and cleans the green pool water – Alternatively, you can use a pool brush if you do not use a pump in the above-ground pool.

In a few seconds, you should be able to see a clear effect from the use of ascorbic acid in the pool.

If the pool is not clear enough, you can try using a little more of the ascorbic acid. Carefully find the correct dosage of ascorbic acid.

At this point, I would like to mention again that the ascorbic acid in the pool does not replace real pool cleaning, and after the party, the water has to be treated with the right chemicals for the pool.

I explain exactly how this works in my blog article, which you can find under the link.

A far better way to clean a swimming pool quickly would be to use a pool clarifier – I recommend always having this in stock.

Clean the pool without ascorbic acid powder

Based on the facts, you decide not to use ascorbic acid powder in your pool.

But how else are you supposed to remove the cloudiness in your pool?

Just stick to the following pool maintenance plan, and the water should be cleaned again quickly.

  1. Start the filter system and let it run through daily for 6 to 8 hours from now on.
  2. Pick up a pool brush and scrub the entire pool.
  3. Next, test the pH and optimize it – if necessary – at 7.2 to 7.6.
  4. Test the chlorine level in the pool. The chlorine content in the pool should be between 0.3 and 1.5 ppm.
  5. Use a flocked pad in the pool skimmer every two weeks. This improves the filter performance of the system.
  6. Place a chlorine tablet in the dosing float so that free chlorine is continuously generated.

After that, the green water should become clear even without the use of ascorbic acid in your pool.

To keep it that way, do not use ascorbic acid in any situation.

The pool also has to be scrubbed with the brush every day – this is simply part of pool maintenance.

Extra tip: If the pool has turned green despite the chlorine, then you probably have too much cyanuric acid in the water.

If this applies to you, drain 1/5 of the pool water and add fresh water. Then the pH level, the total alkalinity, and the calcium hardness have to be optimized again.

I hope that I was able to explain to you in an understandable way why the use of ascorbic acid in the pool is harmful and what an alternative pool cleaning looks like.

Do you have further questions about ascorbic acid?

Contact me on Twitter at @contactswimfool. I am happy to help you.

At this point, I wish you a lot of fun with pool maintenance!

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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 swimfool.com, 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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