That white stippling kind've indicates a potential mite problem. There also looks to be some nute burn on your leaves, but that can also be mite related damage as well. Have you taken in any plants from another grow recently? Do you have a garden outdoors that you visit sometimes before checking our indoor garden? It's summer there are lots of pests out there waiting to hitch a ride on your clothes. What stage of growth are you in? Do you pH check your water/nutrient solution before using it? If so what are your readings like? Is the whole plant affected or is the problem isolated? You need to provide some crucial basic information as to what is going on or else anyone answering is just taking a loosely educated guess based a picture of a single leaf.