Almost all fish are specialized feeders which is why I always say that fish don't need a varied diet, they need what they need and only that. Many fish subsist on a single food and don't need anything else. The vast majority of fish eat other (smaller) fish. In the sea, if you dive you will see millions of fry near the bottoms of rocks. That is the main diet of most fish. Fish fry contain everything a fish needs because they are whole fish and contain everything that is in the predator fish. We as aquarists should try to provide the closest thing we can to what the fish was eating in the sea. Lionfish, trumpetfish, groupers eat fish. They need nothing else. Mandarins and other dragonettes need tiny, whole animals and nothing else. In the sea they eat pods or copepods which is a real animal but any tiny creature will suffice. Then also need to eat every few seconds so "training" them to eat frozen foods once or twice a day is a waste of time as they have no stomach in which to store food. Their short intestine was designed to digest a tiny creature thousands of times a day, not to store it like we do.
Pipefish eat a similar diet to mandarines but most pipefish prefer their prey swimming. Dragonettes only eat fro the bottom as they can't really catch anything swimming. I feed my dragonettes new born brine shrimp every day in a feeder I designed, but when that is empty, they hunt pods. I don't keep a sterile tank and think a sterile tank is a silly idea. Many fish need to hunt and hunting on clean sand equals a dead fish. Fish should "only" die of old age, anything else and we failed.
My normal feedings are live blackworms, mainly for the guts and the bacteria in their guts. I also feed clams that I buy live, freeze and shave off paper thin slices. I like clams because you are feeding the entire animal, guts and all which is what fish need. They do not need squid tentacles, shrimp, scallop, octopus or fish fillets because those foods (when you get them in a sea food store) are only the muscles of the animal and not the guts. Fish are not humans, we throw out the guts, but fish need that. To keep fish disease free, eliminate quarantine and have fish only die from old age, that is what you need to do.
Dry foods although they list a bunch of ingredients are dry. Being dry they would lack fish oils and any bacteria. Fish need to eat bacteria every day to remain healthy, immune and spawning. Damsels like clownfish are slightly different and can live forever on flakes. But they will probably not be immune on that diet.
As for ozone, yes I do use that. I have always used it and am not sure if it does anything. It is used to improve water conditions by oxidizing DOC (disolved organic carbon) or fish and food wastes. It will do little to eliminate any diseases. There are amphipods living in my skimmer so I doubt it will kill parasites.
I also don't want to kill parasites or bacteria. (yes you read that correctly) an immune tank depends on parasites to keep the fish immune. There is more to it than I could post here which is why I wrote a book.
(No I don't want you to buy my book, I am just saying that it is too much to post)
I will try to answer any specific questions or I will link to an article I wrote about it (if I am allowed)
See these little "dots"? Those are fish fry and are all over the reef. I think this was Key Largo but they are everywhere. Remember fish in the sea are always pregnant (like your fish should be) and they spawn constantly laying millions of eggs. That is what the majority of fish eat.
Fry to the left of that lazy nurse shark.
This is a pod or copepod.
years. all are healthy and I've never lost a fish to disease. I have three pair of spawning clowns. in fact back when I was breeding clowns, I attributed black worms for much of my success. 
