Just an update as it has been a while. Shrimps are doing fine, but the diatoms (brown algae) are really annoying. I have two options: leaving the tank so all glass gets covered with the ugly diatoms (and i dont see any shrimp), or cleaning the glass and disturbing the shrimp so they become pale and hidden for 5 days.
Below you can see a picture of one of the full grown opae ula. Unfortunately no berried shrimps het, but guess this would be too soon (shrimp introduced kn the tank in january)