i guess i don't quite understand how nitrifying bacteria can survive in a qt tank. Because a qt tank should essentially have no rock, no sand, just barebottom. And from what i understand it needs more than just the glass to adhere to. how does the bacteria survive for the full 8 weeks?
Nitrification bacteria live in similar way in a QT as in a DT. They live on substrate or medium. The medium can be artificial sponges or polyester floss. I like crushed coral wrapped with tightly stretched out nylon panty hose, to the size of large oranges. 10-12 such orange sized ball will handle a lot of bioload intended for most cases. I think this is most durable and efficient. You can use a simpler medium and less of it for the first time just to get the experience of it. Choose a simple medium for the first experience.
I hope you know that nearly all the nitrification bacteria are bonded onto the substrate, so you can cycle a medium in a separate container and then transfer the cycled medium to the QT. You need to make sure that salinity and ph are close.
You put the cycled medium in a filter in QT. It can be a simple HOT power filter box, or a power canister filter, or a simple wet-dry setup using just a pump.
You may also use the same power filter in a separate container (just large enough will do) while you cycle, as is usually the case. In such as case, I would take the filter medium out and briefly drain the filter after the cycle before putting in the QT. This is because the water you cycle the medium with may be too laden with nitrate , PO4, or other undesirable by-products associated with cycling.
The wet-dry is the most efficient setup, but top efficiency may not be needed. Wet-dry is also very easy to set up DIY, so I prefer wet-dry most of the time when I have a few fish to QT. You don't have to. You can use HOT power box or canister filter.
The only time that you need to worry about the nitrification bacteria is when you use a drug that can harm them; copper is not such a drug, antibiotics frequently are to various degrees.