If they are holes in the leaves that indicates a potassium deficiency. Your plants need macro and micro ferts. You need to read the fertilizer your using to see if it has macro nutrients in it: nitrate, phosphate, and potassium. I dose with dry fertilizers via the PPS-Pro system daily so I know my plants are getting both macro and micro nutrients. Seachem has a line of liquid ferts that you can get for dosing individual macro nutrients, although they are expensive IMO.