PVC pipes are great for QT tanks. If you have bigger fish you will want to consider the size of the PVC. Ceramic decorations and live rock absorb copper medications and so they are generally not used in the QT system. Hypo can decrease the effectiveness of your biofilter depending on how long you plan to have hyposalinity, how much you feed, and how established your biofilter is. Because the bacteria are not in ideal conditions, they slow down. You will want to monitor ammonia. You can use a cheap ammonia alert that you stick on the inside of the tank glass to help keep an eye on the levels and you will also want to use a test kit to confirm. You should switch out the biofilter if the ammonia levels rise. pH is another problem with hypo so you will need to keep an eye on pH and possibly use a pH buffer. Sponge filters are great for QT tanks. I have 3 of them right now in my sump of my display tank to keep on hand if I want to purchase new fish and set up a QT tank. I bought mine at bulkreefsupply.com. As far as Ich if that's what you're treating.. and filter pads... if you want to use a HOB filter then I would suggest a sponge filter pad and a 10 micron filter pad next which may help to catch any free floating parasites and put a new one in daily. Some also recommend a good UV sterilizer, but it's not always an option in the budget.
