The expansion tank of Aqualis series are equipped with a tube made of borosilicate glass, which in contrast to the commonly used Plexiglas tubes for expansion tank has a very high hardness and scratch resistance, very low thermal expansion and excellent chemical and thermal resistance. The glass tube of 100 ml and 150 ml variants has an outer diameter of 50 mm and a wall thickness of 5 mm. Bases and covers the Aqualis series are made of Delrin, lid and base are connected by a steel rod.
The Aqualis D5 100/150 ml variants are designed for direct mounting of a Laing D5 pump at the reservoir. All 100 ml and 150 ml versions are also available with a nano coating is available, allowing the water to pearl off from the inside of the glass tube.