First of all, I am FAR from an expert here, so take this with a grain of salt (pun intended) but I am a big believer in quarantining fish and other livestock, and I do see some red flags that may be a concern....
"We then put our fish through a 3-5 day treatment that targets and cures the many diseases they can come with"
I follow the Reef2Reef approved protocol for quarantining fish,
found here, and it's a 76 day procedure. Some reefers talk about other time frames like 30 days or 60 days, but I don't know of any QT protocol that is both effective and only 5 days long. I see this as a big red flag - either this LFS doesn't know what they are doing, or they are misrepresenting their QT procedure.
"We also keep "all" of our livestock in medicated or slightly medicated (inverts) systems to ensure they remain disease free and healthy....."
I am unaware of ANY medication that's appropriate and effective for inverts at any concentration. Fish are typically prophylactically treated using medications containing copper. Copper at any level is toxic to inverts. The only way I know to QT inverts is to keep them in a fallow tank (a tank that does not have any fish) for a period ranging from 30-90 days depending on who you ask. This will starve out most fish parasites, but there is no medication that does this, only time. Again, this LFS is either wrong or misrepresenting their QT procedure.
I understand that you are trying to avoid the whole QT process yourself, but in my opinion you would be best off to QT your livestock yourself. I personally have three QT tanks going - a medicated fish QT tank, a coral holding/observation tank, and a third tank just for motile (moving) inverts like snails, crabs, shrimp, etc.
I hope this helps and good luck!
