Steve-S, I have to tell you again that I really, really, really appreciate all your help. If I offend you in any way by not taking your advice, I apologise. It's not meant as an insult to you, and it's not me just being stupid. I assume you remember when you first got into this hobby and lots of people told you lots of things about different issues. On the ich issue in particular, I kind of believe the "ich is always in your tank" theory. Please don't be upset about that, though. I've heard both sides argued by a lot of people. This one, I tend to believe the other side, that's all. I still value your advice very much, or I wouldn't be posting here.
Anyway, the cowfish has passed. I still don't have my stupid camera, so I couldn't get a picture of whatever his problem was. My tomato clown seems to be doing fine in the main tank now, though. You remember when I had the nitrite issue, I assume, and I finally got that to go away. My water parameters were perfect... so I added a chromis. I waited a few days and they remained perfect, so I got rid of the chromis and added the clownfish, thus keeping about the same load. Then after they were still in line, I switched out my other chromis for the cowfish. Then the nitrites went back up to about 0.05-0.1. I think that this probably had something to do with his infection being an issue.
I don't know why my nitrites won't stay under control, but the solution is on the way. I ordered a 75 gallon sump setup, and it should be here next week. I'm going to set it up, slowly remove the biomedia out of my bakpak, and then slowly add fish. I figure one fish per week or two starting with the most hardy fish I want and moving up to the least.
I'm also going to get my QT tank going full time. I'm going to buy a couple chromis (maybe one, but probably two) and put them in there to keep it cycled. When I need to put a fish in the tank, I'm going to take them out and put them in the main tank in some sort of container (critter ball, breeder net, etc.) This way I can get them out easily and do the moving back and forth without any trouble. When the QT'd fish is ready to move to the main tank, I'll move the chromis back. This way the main tank gets started on being able to have the load increased and the QT tank stays cycled.
I do have a couple questions about this QT tank procedure I'm planning, though...
1) How long do you think chromis could last in a little critter ball or breeder net without stressing to death? I really hate trying to catch those little buggers because they make me move all my rock just to get them.
2) I would like to have some sort of substrate in the QT tank so it looks even remotely presentable. I know that copper can stay in your substrate almost indefinitely. Is there any problem with new fish getting a hint of copper? Isn't it nearly (if not entirely) harmless to fish as long as it's within the right range?
3) I wouldn't mind keeping the permanent QT tank fish in the QT tank while I'm QTing a new fish for the main tank. However, the fish that seem obvious to use for this task are chromis (or some other damsel). The reason I would move them from QT to main when I'm QTing a new fish is to avoid territorialism, which damsels are prone to, even if it's to varying degrees. Could you recommend another inexpensive, hardy fish that is not prone to territorialism so I don't have to move them?
Again, thank you very much for your help, Steve-S. Although I'm sure it looks like I'm ignoring all of your advice, I'm really not. I value your input, friend. (This also goes to everyone else that helps me. Steve-S just seems to be my biggest helper, along with fishfreek and reefrunner69).