My male gets yeasty, itchy ears in the spring and fall (he's got wicked environmental allergy problems). Diluted apple cider vinegar is my go-to, once every few weeks when they start to get bad. Loosens the gunk, helps keep the pH in balance, gets rid of the yeast, no chemicals.
Like Carmen said, it's important to figure out what's causing the ear issues. Food allergies? Environmental allergies?