Hi, since the beginning I bought Oase Biomaster 600 Thermo, I have a problem with air getting to the filter and then with water getting to the aquarium every few minutes. It was noisy and annoying especially over night time. Been trying to apply silicon greas on each and every seal, which didn't helped. I have had problems to send filter head to Oase in Germany for last 6 months, but yesterday 1/7/2020 it has finally been delivered. Unfortunately I have bought from Aquapet new filter head and yesterday on 1/7/2020 has arrived and been installed, with a bit better results but unfortunately air is still getting to the filter. Really don't know what to think and do at this moment about Oase Biomaster filters. Warm regards.