I discovered Zymox this year too.
On the whole, my lot don't have a lot of ear problems, thankfully, but if they do, it usually costs around £80 at the vets for treatment; so when my Twoee suddenly developed a nasty, gunky, sore ear just after Christmas when funds were very low, I was cursing. One of my other dogs had started shaking her head too, so I treated all the dogs and cats for ear mites (I always have a supply of Advantage Spot on, and a drop of this on the outer ear flaps kills ear mites), but Twoee's ear was still very sore and now looked infected too.
I was telling my sis I was going to take her to the vet, when she told me she had tried Zymox a few weeks before, on one of her Poodles, to great effect. So I ordered some for next day delivery. It arrived first thing and I applied it straight away, and by tea time Twoee's ear looked loads better. Within a week, the ear was perfectly clear and back to looking healthy, and she hasn't had a problem since
I shall certainly be keeping a bottle of this in my doggy first aid box from now on.