You should definitely read this thread. Excellent discussion on alternatives to QT.
I could only get through about ten out of the hundred and twenty-eight odd pages of that thread. Wow!
The fundamental problem with the quarantineless method here -- if I understood it correctly -- is that it presumes that the owner has a mature, fully established tank into which he or she will insert a random fish. Other organisms, which have grown and developed over the course of years, will prey upon any dangerous pathogens introduced into the tank and keep numbers low to the point that they won't kill any inhabitants. It's an exciting, plausible theory...and probably of little utility to new tank owners eager to buy their first fish and who
don't have a ten-year old tank with all of its associated flora and fauna. It also assumes that owners can hop down to the ocean to seed their tanks with "helpful" bacteria and viruses; I certainly don't have access to a beach or ocean, and won't be able to dig into the garden to get some soil until the snow melts three months from now, but that shouldn't stop others who want to try it.
Problem #2: going without QT won't help you with nuisance pests like aiptasia. Or fireworms. The thought of going
au naturel definitely has its charms, but I don't want a garden of majanos in my tanks, either.
Problem #3: While going quarantineless sounds easy -- hey, it's totally hands-off!-- the success stories are largely people who started their tanks many years ago and may have been able to establish super-healthy biomes by buying live rocks and such that were populated with disease-fighting fauna. Many reefers make their builds with dry rock now. Can the same effects be achieved?
Problem #4: the feeding schedules and menus the proponents use for feeding their fish looks kind of complicated. And expensive! I know that this is just good husbandry, and great for the fish, but aside from frozen fish and clams at the supermarket, I don't have access to any of those specialized foods. Just try to source California blackworms in Canada!
Biggest problem:
not one proponent has explained how to replicate their successes by following a formula or plan
using a precise list of ingredients and livestock: you're just supposed to "introduce your fish to disease so that their immune responses can be stimulated/strengthened". And I'm sorry, but that assumption is kind of suspect -- we don't encourage repeated scabies infections in humans, or mange in dogs and cats, because "it will build up our immune systems"; those afflictions are painful and horrible and in pets, sometimes deadly. I can't think why encouraging ectoparasitism in fish will somehow lead to better health. Again, this method might work only because mature tanks have biota that have grown to prey on the predators. In contrast, quarantining has discrete steps and stages that can be understood, and replicated, by anyone.
And until someone can provide a precise, step-by-step guide on establishing a disease-free (or disease resistant) quarantineless tank, that can be replicated by using the scientific method, it's all just guesswork or luck. And I for one don't have a lot of the latter when it comes to reefing.
I guess that I'm just saying that buying two five gallon buckets, a couple of airstones, some HOB filters, and cheap heaters will probably work for you too...until your tank matures and builds up a disease-fighting biome.