Why do sodium ions not continuously build up in swimming pools?

In summary, electrolysed water leaves Na+ and OH- behind, and over time this will lead to the pool becoming saltier.
  • #1
Nathi ORea
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TL;DR Summary
Where do sodium ions go in a pool?
It is killing me trying to understand why sodium ions don't continuously build up in swimming pools.

You add NaCl to a pool. It is electrolysed to H2 and Cl2 leaving Na+ and OH-.

I get OH- builds up over time, and needs to be neutralised by HCl to make NaCl again and water. This would balance out charges, but you quite often put more NaCl in the pool.

I would guess the Cl2 leaves as a gas or perhaps as HCl gas over time, but there must be some mechanism for how Na+ leaves. Can someone help me?
 
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  • #2
No such mechanism, Na+ will build up.
 
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  • #3
Borek said:
No such mechanism, Na+ will build up.
Does this mean that our swimming pools become saltier over time? Does this also mean that we have to add more hydrochloric acid as time goes on too because there is more NaOH to neutralise?
 
  • #4
Nathi ORea said:
Does this mean that our swimming pools become saltier over time?

Yes.

Does this also mean that we have to add more hydrochloric acid as time goes on too because there is more NaOH to neutralise?

No. Amount of OH- produced by electrolysis doesn't depend on amount of Na+ present, only on charge that was passed through the solution.
 
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  • #5
As with any water system, exchanges of water (like splashing water out aand the replacing it with fresh (salt free) water, or overflowing the pool with new water) will reduce the salt levels by actually removing the salt in solution.
A steady state could be achieved if the removal of salt is balanced by the additions of it.

There are several ways to measure the saltiness of water, depending on the range of salinity being measured.

An advantage might of increased salt might be that you will become more buoyant as the salt levels go up.
 
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1. Why do sodium ions not continuously build up in swimming pools?

Sodium ions do not continuously build up in swimming pools because they are constantly being diluted and removed through various processes. For example, when people swim in the pool, they carry out some of the water with them when they leave. Additionally, water is often splashed out of the pool and replaced with fresh water, which helps to maintain a balance of ions.

2. How do sodium ions enter swimming pools in the first place?

Sodium ions can enter swimming pools through a variety of sources, such as tap water, rainwater, and even the human body. Tap water typically contains small amounts of sodium ions, and rainwater can pick up additional ions from the atmosphere. People also naturally have sodium ions in their bodies, and these can be introduced into the pool through sweat and other bodily fluids.

3. Are there any other factors that contribute to the removal of sodium ions from swimming pools?

Yes, there are several other factors that can help to remove sodium ions from swimming pools. One of the main ways is through filtration systems, which physically remove particles and ions from the water. Additionally, some pool owners use chemicals such as chlorine or salt to help balance the levels of ions in the water.

4. Can high levels of sodium ions be harmful to swimmers?

Yes, high levels of sodium ions can be harmful to swimmers. While small amounts of sodium ions are necessary for the human body to function, excessive amounts can lead to health issues such as high blood pressure and dehydration. This is why it is important for pool owners to regularly test and maintain the levels of ions in their pools.

5. How can pool owners prevent a buildup of sodium ions in their swimming pools?

Pool owners can prevent a buildup of sodium ions in their pools by regularly testing the water and maintaining proper levels of filtration and chemical treatment. They can also encourage swimmers to shower before entering the pool, which can help reduce the amount of bodily fluids and ions introduced into the water. Regularly replacing a portion of the pool water with fresh water can also help to dilute the levels of ions in the pool.

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