Ten months after the gigantic AquaDom aquarium in Berlin’s Radisson Hotel burst in spectacular fashion, building owner Union Investment has issued a report on the cause of the damage. However, the essential question remains unanswered as to why the exterior of the approximately 16 m high acrylic glass cylinder suddenly ruptured.

The expert commissioned to investigate the incident, Professor Christian Bonten from the Institute for Plastics Technology at the University of Stuttgart, is quoted in a press release as saying, “We still need to find decisive indication for the source of the damage”, pointing to secondary damage caused by the impact of some of the acrylic glass, which fell at least 8 m.

The forensic examination of the 700 pieces of cylinder rubble – the largest fragment weighs 9 t – suggests three possible causes for the rupture, according to the announcement, which cited the gluing of individual acrylic glass elements during the manufacturing phase, the drying process of the acrylic elements, and a possible notch effect on the cylinder in its base area. However, it was not possible to determine “where the break or crack in the cylinder that caused the damage occurred,” the announcement explained.

In any case, Bonten said he is certain there was no warning about the incident: “The event occurred suddenly and unexpectedly,” the press release from the building owner quoted him as saying. This is likely to be an important finding, particularly for settling claims. Union Investment did not provide any information on the exact amount of damage. The construction of the aquarium, which was filled with 1 mn litres of salt water and housed 1,500 tropical fish, reportedly cost around EUR 12.8 mn when it was built in 2003.

When the AquaDom collapsed in December 2022, around 900 fish died and the hotel lobby and surrounding shops were severely damaged by the force of the water. Miraculously, only two people were hurt, suffering minor injuries in the accident. To date, the hotel has not resumed operations.

Union Investment told Plasteurope.com that Bonten’s written report will not be made public. This means essential details of the damage analysis will be unavailable. It also remains unclear what the inquiry by AquaDom builder Reynold Polymers has concluded. The US company, which wanted to investigate the accident on site with its own team, did not respond to repeated Plasteurope.com queries.

A reconstruction of the aquarium, including the remaining concrete base and the inner acrylic glass cylinder, which is still largely preserved, has been ruled out, according to the announcement by Union Investment.