Is this Calcium Deficiency?

Hey everybody, newbie here. My first grow and i noticed a few brown spots, yellowing tips, a few leaf curling. Running a rdwc setup 4 plants.

slight nute burn = miss a few feeds

good luck

What’s your feed consist of? Ph? Ppm?
what strain you running?
Sometimes people can help better if they see what your using for food, and certain strains use more calcium than others .