How to test chlorine levels in a swimming pool?

Measuring chlorine levels in a pool correctly will ensure the best water quality and give you the assurance that you are swimming in a healthy and clean pool.
It is not enough to simply turn up the pool’s purifier hours to ensure optimal chlorine and pH levels, as well as maximum hygiene.
It is vital to know how to measure and control the chlorine level.
And, come on, you will see that it is a simple task that you can do yourself without getting too complicated and get optimal results, especially after reading our guide to measure chlorine levels in swimming pool.

Importance of testing chlorine levels in a swimming pool

The main importance of maintaining proper chlorine and pH levels in a pool is your health.
When these two elements are level, microorganisms do not proliferate in the water and are not transmitted from bather to bather.
In addition, there is no burning of the eyes or skin and you can enjoy your experience to the fullest.
What happens when the chlorine levels in a pool are not adequate?
Well, high chlorine levels in the pool will cause itchy skin and eyes, eye irritation, hair dye will fall out and your swimsuit will fade.
If it’s too low, there’s no protection against harmful microorganisms that can enter your system.
And the same goes for pH, as it will cause you to experience unwanted chemical burns and irritations.
Another important reason to stabilize chlorine is that it helps reduce costs.
Yes, a pool whose water is well maintained avoids having to drain it all out and refill the pool, which can cost you a few bucks on your bill.
But, it is not the only way to reduce costs, because with solar pool lights you can illuminate your pool at night without spending a single euro in energy because they are charged by the sun.

What are the chlorine limits established by legal regulations?

The legal regulation establishes the following levels of chlorine and pH in swimming pools:
Free residual chlorine between 0.50 and 2.00 mg/l.
Combined chlorine less than 0.60 mg/l.
Maximum total chlorine of 2.60 mg/l.
PH between 7.20 and 8.00.

How to control the chlorine level in a swimming pool

Now let’s look at how to monitor chlorine levels in a swimming pool using all the methods available on the market, from test strips to drops, tablets and digital meters.

With test strips

They are perhaps the easiest way to know the chlorine levels in a pool because they are strips that change colour when they come into contact with the water and, according to the colour scale they give, you can know the level of chlorine by comparing it on a chart.

You can get strips that measure both chlorine and pH levels at the same time, to measure just the chlorine level or the pH level.

And, of course, there are some test strips that measure many more values.

The problem with this measurement system for swimming pools is that there are times when the colour of the result is not very distinct, which makes it difficult to know the precise value.

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With reactive drops

The test drops consist of two tubes that are filled with pool water, one for pH and one for chlorine.

Next to each tube is the colour scale and the values that each of them represent.

In addition, this measuring system comes with two bottles of reagents, which are orthotolidine and phenol red.

You pour 5 drops of orthotolidine into one of the tubes filled with pool water (the one with the same colour as the bottle) to measure the existing chlorine level.

Similarly, for the pH measurement, you apply 5 drops of phenol red to the remaining filled tube.

Gently shake or mix the meter and you will see the water change colour.

To find out the chlorine levels in a pool and the pH, all you have to do is compare the colour of the fluid with the chart on either side of the tube.

The disadvantage of this method of determining chlorine levels in a pool is that it is difficult to differentiate the colour tone.

With reagent tablets

There are cases where the above method makes it difficult for users to apply the exact 5 drops of reagent.

In these cases, reagent tablets are ideal because they work in the same way as drops, i.e. they have the tubes for the pool water, the reference tables on the sides and the colour reaction is the same.

The difference is that you pour a tablet instead of drops.

With electronic meter and test strips

It is known as a photometer, spectrophotometer or spectrograph and is a device that electronically measures the colour of light.

Its operation is simple, as you dip the strip in the pool water, place it in the meter and the digital display shows the exact value of the measurement.

The advantage of measuring chlorine levels in a pool is that it is very accurate and simple.

With digital meter and test tablets

It consists of a glass container into which pool water is added, the tablet is poured and the equipment checks the colour to give an accurate measurement on its display.

The only detail is that the same sample should not be used to measure the chlorine and pH levels.

It must be emptied and the process repeated.

With digital probe meter

If you need to take constant measurements of pool chlorine and pH levels, this is the most economical device because it requires no consumables or reagents.

Simply submerge the device in the water and it will display the values.

How to lower the chlorine level in a pool

It’s simple. Do not add more chlorine, filter the water continuously so that the chlorine evaporates in the water and, if you can, add water as you go through the process to lower the levels.
So, measuring chlorine levels in a pool is easy, fast and effective with the methods described in this post.
And remember, pool lights are an ideal alternative to reduce lighting costs and have a more aesthetic and functional pool, even at night.