All reservoirs of the aqualis series are equipped with a borosilicate glass tube. In contrast to acrylic glass, which is often used for tube reservoirs, borosilicate glass is extremely hard and scratch-resistant, features superb thermal and chemical resistance and a very low thermal expansion. The glass tube of the 450 ml and 880 ml variants has an outer diameter of 75 mm and a wall thickness of 5 mm. Base and top of the aqualis reservoirs are made from Delrin and connected by a stainless steel tube. As a optical highlight, a fountain effect can be realized. If the return line is connected to the center connector of the reservoir, the water flows through the stainless steel tube to the top of the reservoir, where it is ejected through eight nozzles. In combination with illumination, this is a real eye catcher effect. A thin acrylic plate near to the bottom of the reservoir reduces air ingestion to a minimum. Alternatively, the return line can be connected to a lateral connector of the reservoir, the water then exits directly from the base part. For this configuration, a deflector plate is included in delivery to ensure can be installed to effectively remove air from the water circuit.

The aqualis PRO 450/880 ml variants additionally feature an acrylic window in the base part and up to six LEDs (5 mm size) can be installed into the base part. The PRO variants can be upgraded with an electronic fill level sensor at a later date.

The aqualis XT 450/880 ml variants feature the same acrylic window and LED mounting as the PRO variants. Additionally, the XT variants feature an electronic fill level sensor with USB and aquabus interface, a programmable alarm output and an external temperature sensor input. For monitoring and configuration, the aquasuite software can be downloaded free of charge. In addition to the USB interface, the 4-pin aquabus interface can be used to directly connect the fill level sensor to an aquaero 5 controller (not included in delivery). The alarm output can be configured to be used as a rpm signal to be connected to a fan connector with fault detection (for example motherboard fan headers) or to be used as a switched output for example to connect a LED. Fill level and external temperature sensor input can be configured to raise an alarm. The external temperature sensor input is compatible with all Aqua Computer temperature sensors.

All variants are also available with nano coating that will cause water to roll off the inner surface of the borosilicate glass tube.