Just bleach everything and start over with recycling the tank. Make sure to bleach your gravel, ornaments, as well as any filter equipment. Bleaching it is the only way to ensure that the entire parasite is gone completely and that the only way you are introducing it into your tank is by introducing infected fish. All fish carry ich, just like all humans carry strep. When a fish's immune system is weakened because of stress (rapid temp flucuations, water quality degregation, new fish introduction, etc) the ich becomes an outbreak. Just like stress in humans can lead to strep throat.
Ich has three stages in its life cycle. Stage one is a polyp that lives on the gravel, glass, ornaments, and everything else in your tank. This stage is impervious to medications, which is why ich infections become reoccuring in many tanks that are not completely bleached out. This form of the parasite can sometimes stay in hibernation regardless of tank environmental conditions, hatching out when conditions become right again.
Stage two is a free-swimming stages that hatches out of the polyp and swims around looking for a host, aka, the fish. This is the only stage of the life cycle that is affected by medications, which is why most medications require at least a two week treatment period. Frequent water changes during ich treatment also help to remove the free-swimming stage from the water and prevent attachment to fish host.
The third stage is the actually cyst on the fish, which we see as the little white spots. This stage is also impervious to medications, although it can sometimes be combated by changes in osmotic pressure, aka the addition of salt to the environment which will suck water out of the cyst (as well as out of your fish) and cause the cyst to implode, rendering it dead. Once the cysts develop, they fall off the fish and into the sesile stage on your gravel, glass, ornaments, etc. to restart the cycle.
It is true that in an unpopulated fishtank, you can get rid of ich simply because there is no host. I recommend keeping the tank unpopulated for at least two weeks to be sure the parasite has starved itself out. Elevated temperatures are known to speed up the parasite life cycle, thus making them hatch out into the free-swimming stage faster, thus starving the parasite faster, but as I said before, many parasites can go into a hibernation and wait out bad environmental conditions, so you will never be 100% positive the ich is gone from your tank. The parasite is not all sycronized at the same time, so you can have many different individuals in different stages of development at the same time. One week of medications may have gotten rid of one stage, but the two other stages still hatch and continue the life cycle, thus perpetuating re-infections even if the fish were spot-free a week before.
Like I said before, just bleach it. So long as you aren't hurting any fish in the bleaching process and you don't mind the patience of having to recycle the tank, there is no harm in bleaching anything. If you are afraid of bleach residue, soak everything in a bucket of water with dechlorinator (tap water conditioner) in it, that should remove any bleach residue. I don't recommend bleaching driftwood, and if you do, soak it at least a week in un-bleach water to make sure everything is completely washed off.
~~Colesea
I am asking how long it will take to die off in a completley EMPTY tank...as in, when I take the fish out, how long will it live in the tank WITHOUT A HOST? As in, do I need to bleach the tank out to eradicate what would be left in there, or can I just leave the tank empty for a few days and it will die because it has nothing to attach on to?????