Another thing I used to do with our springer spaniel was to shave the underside of her ears and the area that the ears covered when flopped down. It helped somewhat with the air circulation and quicker drying. Once the infection was healed I would regularly squirt a mixture of equal parts rubbing alcohol/white vinegar/water into the ears and "sqwirch" it around so it would reach way down into the canal (which is L-shaped and long) to make a hostile environment for yeasts and bacteria.