Hello, can anybody tell me what's going on with my discosomas?
I am keeping them in my tank since months without any problem. They always grew fine and wednesday were like this:

However since saturday they are like this:

Thing is: I have several colonies and they all look the same, quite contracted. All other corals (soft and LPS) are ok. No recent technique changes to the tank. I just added a quadricolor 10 days ago, might it be disturbing the discosomas by releasing some compounds?
Otherwise:
50 liters
60w led light
total of 3000 l/h of flow
Values are very low: NO3 1mg/l and PO4 0mg/l
Thanks in advance for your help.
I am keeping them in my tank since months without any problem. They always grew fine and wednesday were like this:

However since saturday they are like this:

Thing is: I have several colonies and they all look the same, quite contracted. All other corals (soft and LPS) are ok. No recent technique changes to the tank. I just added a quadricolor 10 days ago, might it be disturbing the discosomas by releasing some compounds?
Otherwise:
50 liters
60w led light
total of 3000 l/h of flow
Values are very low: NO3 1mg/l and PO4 0mg/l
Thanks in advance for your help.