pH value

pH value

The pH value of pool water is a very important factor. A wrong pH value can cause many problems. The pH value, which should usually be maintained, can be exactly calculated by means of the Langelier-index. As a guide on our labels we indicate a desired pH value of 7.2 – 7.6. This value works in practice.

The pH of the water can change by:

  • Flow of water
  • Adding certain chemicals and by reaction with other chemicals
  • Tap water, dust and organic material which lands in the water by wind and/or swimmers


PH corrections should be done in small steps. Increase or decrease the pH value in steps of 0.4 maximum per time. Turn on the pump. Afterwards wait for 8 hours (24 hours preferably) before taking a next step.


A maladjusted pH value can cause many problems:

Problems with a too low pH value (corrosive water)

  • Stains
  • Metals dissolve (corrosion)
  • Eye- and skin irritation
  • Formation of chloramines
  • High chlorine use (unnecessary)

Problems with a too high pH-value (alkalinity)

  • Blocked filter
  • Less water circulation
  • Cloudy water
  • Problems to maintain water balance
  • Eye- and skin irritation

If the pH value is too high or too low, the total water balance cannot be properly maintained. The pH value of swimming pool water should be measured regularly. The pH value can be corrected using Melpool pH- or Melpool pH+. When the pH value fluctuates widely and/or has high peaks and troughs, the Total Alkalinity (TA) value should be checked. Without good alkalinity in the pool, the pH level will not remain stable. And therefore there is no proper water balance.

Products for pH value

pH decreaser for swimming pools.

The pH value is important for optimal performance of chlorine/disinfection products. Also lowers Total Alkalinity (TA value). High-quality, fast-dissolving granulate.

pH increaser for swimming pools.

The pH value is important for optimal performance of chlorine/disinfection products. Too low a pH value can lead to corrosivity (filter pump). High-quality, fast-dissolving granulate.

Increases the total alkalinity for swimming pools.

Granules to increase the Total Alkalinity (TA value) of the pool water. A deviating TA value has a negative influence on the pH and disinfection. High-quality, fast-dissolving granulate.