Testing water quality

Aquaria which are set up according to the DENNERLE system virtually rule out problems from the outset. For safety's sake, regular monitoring of the key aquarium water values is nevertheless extremely important.
DENNERLE Immersion Tests enable straightforward measuring in a matter of minutes.


The ideal values for aquarium water (community fresh water aquaria):

  • Carbonate hardness 1-4 °d.
  • Total hardness 4-7 °d
  • pH value 6.4 – 6.9
  • CO2 content 20 – 35 mg/l
  • O2 content, in the morning 3-5 mg/l
  • O2 content, in the evening 5-8 mg/lKarbonathärte 1-4 °d

What needs measuring, and when?
When the following changes take place in the aquarium:

  • Water changing:
    When new water is added to the aquarium, e.g. osmosis water: KH, total hardness, pH, CO2, O2, nitrate.
  • When replacing old lamps:
    pH, CO2, O2  over approx. 4 weeks; measure daily at first, then later every 2-4 days, adjusting the supply of CO2 accordingly.
  • When introducing new fish:
    pH value, O2, nitrite and nitrate in particular prior to introducing new fish and in the first few days after introduction.
  • When setting up a new aquarium or carrying out extensive rearrangement:
    pH, CO2, O2  ammonium/ammonia over approx. 4 weeks; measure daily at first, then later every 2-4 days, adjusting the supply of CO2 accordingly.
  • If fish behave unusually, e.g. gasping for air or "darting about": pH, O2, ammonium/ammonia, nitrite, nitrate  
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