Is this a cal deficiency?

Hi there, without more information, like the growing medium (i.e. whether it's pre-fertilized soil) and the EC values of your nutrient solution it's a bit difficult to say, but it looks like a deficiency to me.. are you using tap-water or RO water, and if tap-water, do you happen to know the EC value? PH of 6.3 sounds ok for soil (if soilless, then it should be lower) happy growing