Checking the chlorine level in a pool is not as simple as you might think.

That's why the test should be put in the hands of the professionals, especially if we are talking about a pool that is in constant public use.

Hotels and resorts will need to know exactly what the chlorine levels are at all times - and it's not just the chlorine which needs testing, but other chemicals and hygiene routines, too.

Hotel guests are increasingly aware that a well run leisure facility needs more than just a lifeguard on hand to ensure that spa heaven does not turn into spa hell.

It's up to the operators to put in place the right safety and maintenance procedures.

It is not just a question of keeping an eye on the customers, but on the equipment and facilities they are using as well, including the very water they are enjoying splashing about or swimming in.

Did you know, for instance, that there is a difference between free chlorine and total chlorine in a pool? Similarly with bromine.

'Free' chlorine is the level of chlorine left which is able to efficiently sanitize the water. 'Total' chlorine is the level of both free chlorine and chlorine molecules which are 'spent', known as chloramines and therefore no longer doing the sanitizing job efficiently.

So it is important when testing swimming pool chemicals not simply to just gauge the total chlorine level, but to know exactly how effectively the free chlorine is working.

The readings will be different depending on how often and how well the pool water is 'shocked' and oxidised, and professionally cleaned.

It is also important to check the pool water's PH level, testing the acidity and alkalinity of the water.

Unless you know the true chemical balance of the water you could end up with a pool that no-one wants to swim in - or worse - one that leaves customers feeling ill or in danger of acquiring an unhealthy infection.

That is why you should always call in the professionals.