By appearances it seems your root zone is saturated. I noticed you're using rock wool croutons which should provide enough air to keep things in check. A wet or saturated root zone prevents the plant from taking up water since it is thoroughly hydrated.
Calcium is an immobile nutrient and can't be transported to other parts of the plant if it's overwatered. Even if there is enough present in your nutrient solution. That's why you see the yellowing around the leaf edges. This will cause other issues as @ken dog pointed out.
What's your watering/feed schedule and what type? Ebb and flow, drip? What nutrient set up are you using and what is the pH?
I think you will be able to correct this with an adjustment to either your watering schedule and/or a pH.
Can also be a result of high humidity, especially during dark periods. Getting better ventilation or dehumidification would be the answer if that's the problem.
I'm not an expert but all your symptoms seem to indicate too much moisture, whether it's in the root zone or environment.
Not too complicated a fix if that's the the case.