My tank has sat in this spot for years, its about 5 yearssih. When I clean it (every 1-2 weeks) i do a 50% water change. I built my filter from scratch, so I cant pin point whats in in it. I dont know too much about fish, so I dont know too much, sorry for that. For better info, I have 2 skirt tetras in my tank, and 2 fish I sadly dont remember what they are called, but I know they eat only algae. Jermey, I dont understand too much of what you are saying, can you please explain in a simpler form, again, my apologizes, i dont know too much.
Sorry, about that, I sometimes get too technical.
If the tank has been running with fish in it for more than a couple of months, normally it would be fully Cycled, and you can disregard my previous post.
An exception would be if you cleaned your filter with tap water, or recently replaced all the filter media at once, this can kill the good bacteria and restart the cycle, causing new tank syndrome, even if it has been running for years.
On the other hand, if your hospital tank has been without fish until you added the sick ones I would keep a closer eye on the ammonia than usual.
If you don't have a test kit, and you just started up the hospital tank from storage or standby, I would change about 50% of water in the Hospital tank twice a week to avoid "new tank syndrome" adding to the current troubles of your sick fish.
Since you recently had a fish die, this could have caused an ammonia spike.
I would advise saving some water for testing, then doing as big a water change as possible without the fish seeming stressed, while vacuuming the gravel as thoroughly as possible. (You want to go for around an 80% to 90% water change)
Don't forget to unplug your heater and filter if they will be out of water.
This will serve to dilute any ammonia, Phosphates, Sulfur, nitrite, or nitrate (these are pollution from dead fish, uneaten food, fish manure, etc, the most dangerous being ammonia and nitrite), as well as reducing the number of disease organisms in the tank.
If you don't own a test kit for ammonia, nitrite nitrate, and ph, see if you can get your water tested at your fish store, many will test water for free.
You want the results in numbers, if they can't be that specific, they are not using a very good test.