Possible deficiency or calcium needed?

Here is a good website with pictures to help identify some plant problems: https://www.growweedeasy.com/cannabis-symptoms-pictures Good leaf pictures are very helpful but it also helps to know where the problem leaves are located on the plant. If they are at the bottom it can mean something different than if they higher up on the plant. It does look like you might have a pH issue. Try adjusting your water to 6.5 pH for all waterings. To make it easier and for consistency I use a large bucket with a lid and pH adjust about a week's worth of water at a time. I use Ocean Forest with great success. I start adding nutrients when plants are about the size of your Sour Kush & Critical Purple. When you have problems appear on the lower leaves it often means it is a problem with a mobile nutrient like N, P, K and magnesium. The plant doesn't have enough nutrients for it's new growth on top so it robs mobile nutrients from the lower leaves. Other nutrients like calcium don't move within the plant and a problem with them will show up all over the plant or on higher leaves.