Some advice

Everything you need to know about the pH-value…

The pH-value is an important indicator for the quality of the swimming pool water. It serves as a measure of the concentration of active hydrogen ions in an aqueous solution and indicates the extent to which this solution is acidic, neutral, or alkaline. The pH-value of pure water is 7.0; acidic solutions show a pH-value of less than 7.0, and alkaline solutions a pH-value between 7.0 and 7.4. Formerly, a pH-value of 7.2 to 7.6 was recommended. So why this change of mind? Has our water changed in some way? Of course not. However, according to today’s knowledge, a pH-value of 7.0 to 7.4 is considered as being the best compromise because it has a positive effect on the germ killing speed of disinfectants and flocculants.

When and how should I carry out the disinfection?

Important! Disinfection only makes sense after the pH-value has been adjusted to the ideal 7.2 to 7.4. Then, a minimal amount of disinfectant ensures an optimum effect. The mucous sheath of the algae can only be permeated and its growth slowed down when there is a high excess of free chlorine (>8mg/l). This can be achieved by means of a chlorine shock treatment (e.g. with hth chlorine granules). It is most advisable to add the disinfectant in the evening, after bathing. The next morning, you then have to measure the chlorine content and decide:

whether you have to repeat the chlorine shock treatment (free chlorine < 0.5 mg/l)
whether you can start bathing again (free chlorine between 0.5 and 3 mg/l)
whether you have to wait until the chlorine content has dropped to a reasonable level (free chlorine less than 3 mg/l).

And what about the algicide?

Even with a constant chlorine excess you should use an algicide (Algenex ‘S’). As you know, algae are plant-like microbes which may multiply at great speed in the water of the swimming pool. The most common are green algae which cause a green colouration of the water and slippery coatings on the floor and the walls of the pool. Algae can become resistant to a constant chlorine excess. In order to stop the algae from growing, we recommend the regular addition of an algicide, e.g. Algenex ‘S’, in addition to disinfection.

There are two types of filters for swimming pools.

The sand filter
This is the most common swimming pool filter. It is considered as being the best compromise solution because its maintenance is easy and the water becomes perfectly clear with the help of  flocculation (e.g. Superflock c - cushions).

The cartridge filter
This is mostly used for smaller pools and whirlpool baths. The filter elements can be hosed off and cleaned. However, flocculation is either impossible or only possible to a very limited extent.

Why should I backwash?

Capturing debris will cause any filter to ultimately clog up. By backwashing it, the filter becomes clean again. At high pressure, water is pumped into the filter tank from underneath, therefore in the reverse direction. This causes the sand grains to rise so that the debris can detach from them and be washed into the drain with the outflow water. The more water that drains off through the backwashing, the more fresh water has to be refilled. This is important because any chlorides and sulphates which remain after disinfection can only be reduced through water dilution (through adding fresh water).

How long should I backwash?
In addition to choosing the right time to do the backwashing, its duration is decisive. Depending on the debris and the backwash pressure (this varies according to pump performance), it should be between 4 and 6 minutes. The sight glass shows when the backwash water is clear, i.e. the filter is clean again. The second criterion is the amount of fresh water that needs to be added. 3 to 5 per cent of the total volume should be replaced on a weekly basis.

When do I have to replace the sand?

Filter sand is subject to wear, too. The individual grains have – when they are new – a defined size and very sharp edges in order to capture the dirt particles in the optimal way. With every instance of backwashing, the grains of the sand rub against each other and therefore become increasingly smaller and rounder. To ensure the best filter performance possible, we recommend that you replace the sand after 1 to 2 years.

We carry out a water analysis with reference to the most important parameters so that we are able to provide you with individual advice as to how to monitor your water values. This will mean you are always able to have crystal clear and clean water.

Kupsch Schwimmbadtechnik GmbH