if its mites, you need to check under the leaves that have tiny spots. your looking for tiny white clusters that look like grains of salt, maybe only 4 or 5 grains. then look for tiny black grains of salt. use a 30x to look at these things if they are they, keep looking under all the leaves till you find these. next if you have any buds, used a scope again, what your looking for is what looks like super thin micro fishing line going from one part of the bud else where, just little fibers, thats the webbing they make, they will make the webbing in dense parts of the plant. you need to check your plants often for mites, they can go un noticed even on healthy looking plants but it only takes about a week for them to spread to all plants. first hand experience, once you notice them, all of your plants are most likely infected and need to be taken care of, with special attention to all clones to prevent future spread.
neem oil will be a good preventative to get rid of the damn things but it needs to be applied appropriately, you can find a guide on the subject. also chems can be used but is frowned upon for those pro health due to their long half lives and residual activity.