First thing is to clean and calibrate your EC meter to make sure it's accurate. Next flush your pots until the runoff ec is down to a reasonable range say 1.2 ec. Weather your in coco or peat you should always check your runoff ec to make sure your plant is feeding what your putting into her if not it will build up which is what your dealing with. I check my run off at least once a week. Hope this helps.👍