+1 on everything Paul said. Also, dont add the stress zyme, just my opinion. And speaking from experience, a 10g is not large enough for a qt tank. Remember, that in a qt you will not have the added biological filtration from sand and rock so you will need a seriously heavy duty filtration system and need to have lots of saltwater ready to do frequent water changes. Since you do not have a qt set up and cycled already, I worry that moving your already stressed and seriously sick fish into an even newer tank than the one he is in will only make matters worse. The reason your fish has ich is because of the little mini cycle you had. Most all tanks have ich present, but a healthy fish has enough slime coat to prohibit the bugs from attaching. When they are stressed from things like the presence of ammonia, nitrates etc. their slime coat is compromised and they become suseptible to ich. The best thing you can do right now is get your tank parameters in line. Your nitrites are fine as long as they stay under 20ppm any nitrates over a long period of time can kill fish and ammonia will kill fish. Also, I am willing to bet that your inverts all died because of the tap water. They are very sensitive to copper and most city water runs through copper pipes at some point. Ergo, dont use it. So if I were you I would just work on the tank you have and get a 20g set up as a qt for future use. I have had fish come back from serious bouts with ich with no treatment. And I killed a fish by putting into a 10g quarantine that was newly set up. This is just my 2 cents. Im sure some people may disagree with me but, IMO you shouldnt put a sick fish into a new 10g QT. It will only stress him out more. If you want, I can lend you a 37 g and a marineland 280 filter. I would fill it with water from your tank, and do very frequent water changes. Pm me if you need the tank, sorry this is such a long post. I have had my share of experiences in this department.