swimming pool spa water treatment by uv-c ultraviolet disinfection BIO-UV Group

Water upkeep

Some reminders and tips for effective long-term upkeep of your swimming pool/spa water

To keep the water in your swimming pool healthy and transparent, both the pool and its equipment must be regularly maintained. To help you with these tasks, BIO-UV sets out the basic rules for effective water treatment and informs you about the main elements present in water.


To date, more than 70,000 privately owned pools (swimming pools & spas) around the world have opted for this system, to the delight of their users ! Owners of a BIO-UV system for treatment of swimming pool or spa water benefit from unbeatable water quality.

Water balance is a permanent objective. It is achieved by controlling 3 key parameters.


Indicates the alkalinity or acidity of the water. It is usually preferable to keep the pH at around 7 (neutral). It is not affected by the action of the UV-C lamp for water treatment.

If less than 7: acidic water, corrosive for the skin and pool surrounds
If greater than 7.4: possibly uncomfortable for bathers (stings the eyes), facilitates growth of algae and calcification, makes flocculant ineffective



This is water hardness, i.e. the calcium and magnesium content.
If the value is higher than 25°, it is preferable to add a calcium sequestering agent once every season (e.g.: BIO-UV ANTI-CALCIFICATION).

Very hard water leads to limescale deposits and damages piping.
If the water is too soft (acidic) it may be corrosive.


Methyl-orange alkalinity (TAC)

This measures the bicarbonates and carbonates content of the water, i.e. its alkalinity.

It must be between 10° and 15°.
It can be modified using appropriate products: TAC+ or TAC-

They are many different elements present in water. They have a detrimental effect on water quality:

  • Algae: these plants can grow in the basin, they are transported in large quantities by air. To prevent them from developing, a disinfectant alone would be consumed first to the detriment of its bactericidal action. We therefore recommend that in addition you should use residuals plus a BIO-UV algicide SPECIAL CONCENTRATED ALGICIDE  (swimming pool product)
  • Organic matter: carried by bathers and the natural environment, not harmful; this must be retained by filtering and the various treatment processes
  • Micro-organisms: bacteria, viruses and fungi are carried by the same channels and can be harmful to health; the role of  BIO-UV water disinfection is to destroy them
  • Metallic ions: iron, copper, manganese, etc. They can be found in large quantities in well water or following crop protection treatments (sulphates). These ions can also damage pool surrounds (liner) and discolour the water. It is possible to sequester these ions using specific products 
  • Phosphates and nitrates: they can be present in highly variable quantities and facilitate algae growth. They can indicate pollution of the water table

Avoid using well water

Taking into account the area surrounding the swimming pool and the way it functions, it is vital to point out the fundamental rules that must be followed with the different parameters such as flow, filtering and water balance that make it possible to achieve water quality that lives up to our expectations, regardless of the swimming pool water treatment used, while reducing the input of different chemical products and avoiding unpleasant and costly mistakes.

Prevention = happiness and savings


Pool hydraulics

The water must circulate throughout the whole of the pool. The number of discharges, skimmers (or overflows) will provide this circulation and make it possible to minimise the number of "dead zones". The capacity of the swimming pool pump must of course be in proportion to the relevant volume of water so that it can be entirely treated within a reasonable period of time (4 to 5 hours). The diameter of the piping must also be in proportion to the swimming pool volume.

Poor flow rates = development of algae and bacteria



Filtering is a vital factor for treatment of swimming pool or spa water. Its role is to retain suspended solids and the different particles in the filter mass.

Effective filtering makes it easier to economise on use of disinfecting products (swimming pool product).

Each filter must be maintained: carry out a backwash once a week.
It must be cleaned and de-scaled 1 once a year using a special product (e.g.  BIO-UV FILTER CLEAN) to eliminate calcification deposits and clogging matter).

The filtering time must be respected
Basic rule: half the water temperature.
If more than 28°: filter 24 hours a day.



In the case of a sand filter, it is necessary to add a flocculant or clarifying agent in order to increase the filter fineness.

WARNING: never flocculate if you are using a diatomaceous earth filter.

Obviously the filter size and capacities must be in proportion or even over-sized in relation to the throughput of the swimming pool pump