Why Does My Pool Have a Strong Chlorine Smell?

Why Does My Pool Have a Strong Chlorine Smell?

“My pool had a strong chlorine smell”. This is what a customer told me on the phone recently.

I then attempted to explain to the customer that our company had treated the pool with a super shock of chlorine in order to eliminate the problem.

The customer had many questions, and I felt ill equipped to answer them as to why having a strong chlorine smell in the pool did not mean that the pool had too much chlorine.

So, I will explain the reason for the strong chlorine smell.

All Pools have Free Chlorine and Combined Chlorine.

Free chlorine is the chlorine that is responsible for continuously sanitizing the pool. In order for the chlorine in a pool to properly sanitize and kill microorganisms in the water, it needs to be at least 2.0; Anything above 2.0 is always good.

(We prefer to be at least 3.0.) But, if it is at least 2.0, we will check other factors that may be inhibiting it from rising to 3.0. In order for free chlorine to work properly, the two other tests, PH and alkalinity, need to also be in range.

If they are not in range, then the chlorine cannot work properly and sanitize the water.

When swimmers get into the water, their natural sweat, saliva, body lotions, hair care products and other fluids go into the pool water. All these factors make the free chlorine lose its effectiveness.

Overtime, the chlorine, as it’s broken down by sanitizing the water, is reduced to combined chlorine.

Too much Combined Chlorine in the Pool can inhibit the effectiveness of Free Chlorine.

I’m not a chemistry major, but when there is too much of the broken down chlorine in the water, it inhibits the effectiveness of the free chlorine.

Combined chlorine is a form of chlorine that does not have the sanitizing power of free chlorine. Combined chlorine does not show each time you test the pool. Over time the combined chlorine can build up in the pool.

A pool professional knows that there is too much combined chlorine in the pool when they can’t get a chlorine reading and all the other chemicals tests are in the normal range.

Shocking the Pool with High Doses of Chlorine Shock will Remove Combined Chlorine.
This will also remove the smell of chlorine coming from the pool. If we have issues with too much combined chlorine in the pool, then we will super shock the pool overnight.

After super shocking the pool, the chlorine readings will be high but once the super shocking is over, bathers can still get in the pool even though there are high levels of free chlorine present in the pool.

Customers sometimes ask if there is a way to prevent the combined chlorine from getting to high levels.

The answer is yes and no. Yes, we do seek to monitor the chemicals on the pool on a weekly or bi-weekly basis.

That way, we are constantly making sure that there is sufficient free chlorine in the pool. However, there are constant challenges with regulating pool chemistry and nothing is a perfect science. So, no you can’t ever completely prevent combined chlorine from being in the pool.

Anytime you are dealing with a body of water between 10,000 to 90,000 gallons, then there will be challenges.

Our goal as pool professionals is to maintain the pool chemistry at each pool we service so the only thing that our customers have to do is enjoy it.

When issues arise, we seek to resolve them as soon as possible.

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