Why do so many still have problem with ich?
1. Faliure to appreciate that a tank is both pathogenically and chemically closed. Failure to understand why some diseases have to be eradicated. Failure to understand why other diseases cannot and need not be eradicated. Failure to understand why chemical water quality and nutrition are necessary but insufficient. Failure to understand the limited significance of enhanced immunity for some diseases such as ich.
2. Failure to understand and be good at procedures even after knowing 1.
3. Practically speaking, failure to cycle medium for QT well enough to usually remove the problem of ammonia during lengthy QT.
4. Failure to understand the difference in chemical water quality requirements between a reef DT and a fish QT. Needless complication over something that should be simple.
I think I am pretty good at 1, 2 & 3. The only thing I monitor and test for in QT is Ammonia. Compared to DT testing for Ca, ALK, Mag, PO4 and NO3
I think one of the top reasons new tanks (not necessarily new hobbyists) get ich is because the tanks are too sterile. The bacteria levels are still low and not fully matured; that is an unforseen contributor to stress in a new setup that people seem to ignore.
If you look at people who have serious wipe outs from ich *most of them are newer tanks (again not necessarily new hobbyists). Old mature systems handle stress and therefore ich much much better (not that ich can't wipe out a mature system but it doesn't seem to be as common imo).
Such vagueness is not necessary, and likely detracts from the truth importantly.
First, as far as fish are concerned, ich outbreak is because ich exists in a tank.
Second, as far as fish is concerned, a tank needs not be "mature"; rather, the medium that does the biological filtration should be robustly circled.
The time it takes for an almost sterile medium to become a powerhouse in maintaining excellent water quality (for fish) is always about 5 weeks +- a few days, when the setup is proper. Within such a time, with enough medium, the medium will handle practically limitedless bioload in QT, even several huge 10-inch fish all at the same time, as far as having zero ammonia.
In fact, a mediun may have more bacteria after 5 weeks then it would ever have, even in another ten years of moderate bioload. During a cycle, the medium could have processed many times the ammonia and in very compact time frame that could ever be generated naturally by livestock, even after twenty-fold increase in size of the livestock.
So here is where I am confused. Assuming no system upgrade (which would be an optimal time to start quarantining) how does a small tank person start QTing? For example let's say I wanted to add a more expensive fish which I wished to QT. What would be the purpose if it then goes into a healthy tank which may have diseases not showing symptoms?
As far as the morality of QT and husbandry I find it funny where lines in the sand get drawn. So you're okay with the high % of fish that died at the wholesale level so you can get yours, but once it's in your care it's another story? Or even if you go completely captive bred (everything living in your system) all your equipment comes from manufacturers that are supported by the larger industry. I'm certainly not suggesting others adopt my views and I'm not looking to adopt others' views.
Ignoring the moral aspects, here is the monetary reason for QT.
Fish usually come from the LFS undernourished and stressed. Even if they don't have any diseases, their resistance is very low. QT is a fishie 'spa day'. It's a chance for them to relax and recover. It's a chance to learn to eat the food you'll be using in the DT.
If the new fish does have a disease it's your only real way to threat it and keep the disease out of the DT.
Let's look at the cost of a QT.
Ten gallon tank - new $10, used free?
Heater - $25 (also a backup if your DT heater dies)
HOB filter - $25 (keep some media cycled in your DT)
Some PVC fittings - $5 (for hiding places)
Salt water - $5
So for about $70 you can have a QT. About the price of a fish. If you save the life of just one fish you have broken even.
No brainer.
QT doesn't need to be set up and running all the time so there is very little continuing expenses.
Petco is a huge contributor to Ich in home tanks for new hobbyist
Vagueness? It's a theory not an exact science...
I have know a lot of lfs that were very experienced and knowledgeable who had big losses (fish) the first 9-12 months but then everything magically got better, much better. Nothing changed other than the systems became "mature" (I use that vaguely because I don't care to really go at length to discuss it) and the fish mortality rate dropped down to almost nothing. Did they magically learn to cope with ich that comes in on livestock that comes/goes through their tanks or did something change in the tanks over time that helped...
Different scenario...When there is no ich in a system there will be no ich outbreak. Very exact.
Ich can be eradicated. Very exact.
From almost sterile, medium to process ammonia can be developed to maximum in about 4 weeks. Very exact.
Nitrate and PO4 to a level undesirable to a reef DT is quite acceptable for QT of fish. Very exact.
Different scenario...
Dealing with ich in a system.
New vs mature systems.
New handles ich poorly and high mortality rates ensue.
Mature handles ich very well, no deaths.