"Long therm test unit for CO2 and pH • Comparison of staining of liquid against a colour-scale adhesive label enables both the CO2 content and the pH to be read at all times. • IMPORTANT: Also includes the carbonate hardness. • Accurate reading through white background in the test container.
Product description The JBL Permanent Test CO2 plus pH is a beautifully designed unit for attaching inside the aquarium which permanently displays the pH value or the CO2 content of the aquarium water. Two separate colour scales, one for pH and the other for CO2, are included with the unit to be attached to the pane of the aquarium, as required. Test principle : An indicating device contains an indicator liquid which is separated from the surrounding water by an air pocket. Making use of a trick from physics, the indicator liquid shows the pH level resulting from the CO2 level in the surrounding water. This allows a colour value for the correct CO2 content to be calculated. Gases have the characteristic of balancing their partial pressure (concentration) at boundary layers between water and gas (in this case water and air). The same CO2 partial pressure therefore develops in the air pocket between the aquarium water and the indicator solution as is in the water. This partial pressure is also passed on to the indicator liquid. As a result, after a little time, the indicator liquid acquires the same pH level from the CO2, as the surrounding water. The indicator changes colour according to the pH level. The air pocket is vital for the pH level to be displayed precisely, as the indicator would otherwise mix with the surrounding water and fade. Use as CO2 permanent test: Independent of the carbonate hardness, the CO2 level in the aquarium can be checked via the pH level arising from the CO2. On the colour scale, three different colour fields therefore display the correct colour value for the best CO2 levels for three hardness levels. First a CH test should be used to measure the carbonate hardness in order to select the right colour field for the aquarium in question."