Well the reality of it is that a true hospital tank likely needs multiple water changes daily. (which means a cycled filter is not really necessary either as you should be doing large and frequent water changes to the point that you'd never see any ammonia etc build up). So if you're not physically there for more than half the week that sort of make a hospital tank un-obtainable anyway.
The impact of having the sand in the tank means you can never truly do a thorough cleaning (at least not to qt/hospital tank standards) and there are lots of things that could negatively affect a fish that can thrive in that sand. For most display tanks with healthy fish this is a non issue.
A quarantine tank on the other hand is literally to quarantine (to isolate and/or keep separate from) your other stock. Usually not the worst idea to quarantine any new fish and keep them in a dedicated tank so you can observe them for a few weeks. Hopefully, you never see any issues with those new fish and can place them in your main tank after that observation period; or you find an issue and begin treating. This second scenario is why most people dedicate a bare bottom tank as a qt setup which they can medicate if needed (basically turning the quarantine into a hospital tank).
What is it that you keep and why do you think you might need the qt setup?
So the 180 I have now is torn down, because I got hit with Columnaris, that and the fact I just bought a ton of drift wood from Tom Barr. So the 180 been cleaned and about to start doing a new scape. I don't want to take any chances this time.
The wife is willing to add medication to anything we put in QT so on, do water changes. Well at least she says she willing to do that
So in the order to save money and since the 40 is already up and running, cycled as well, should I just pull the rocks/sand out of it and that will be my qt/hospital going forward? I am thinking trying to use it as grow out tank for plants so on will be more trouble than it worth since I am out of town so much.
Bottom line is I want the QT to avoid being burned again. I think I am making the 40 QT more complex than in needs to be. I guess I am thinking long term after I get all the fish I want in the main tank, what do I do with the QT tank, I assume it always good to have up and running.
I guess it would only cost me about 30 bucks to setup 10 gallon QT, but I guess is it worth it to have another tank since I already have the 40. Might be more trouble than it worth, since I am out of town so much.