Reddit mentions of Seachem MultiTest Copper Test Kit

https://www.who.int/water_sanitation_health/dwq/chemicals/copper.pdf

WHO says if it is above 1.3 mg/liter it has to be reported to the EPA, so anything less and you are safe. You can test your water yourself using an aquarium copper test kit. They're sold on Amazon
https://www.amazon.com/Seachem-MultiTest-Copper-Test-Kit/dp/B0002A5XGO/
and probably at your local aquarium/pet store. The one I linked has a really good sliding color scale so you get more 0.1 values than other test kits which just give you only like 4 color values.

I think that is to small. Personally when I had my qt tank (turned into a real tank haha) I used a 20 gallon marineland kit. I think it was 100$ it needs to be big enough for all your fish to be able to live not stressed out. You could attempt a solution that is not copper ( may work but may not ) in your DT. My LFS uses herbtana when they can't copper treat a tank. Seem like ok stuff, I've used it in my 40b DT and all my corals where fine (never used it for ich). but I know lots of people hate all solutions other than copper.

http://www.amazon.com/gp/aw/d/B00345XZBO/ref=mp_s_a_1_1?qid=1419736741&sr=8-1&pi=AC_SX200_QL40&dpPl=1&dpID=415tOR1fboL&ref=plSrch

Copper is the best bet but takes a lot of set up plus it won't be cycled. You could use 10-15 gallons from your DT and use that as a 50-75% water change on it. Just to get the cycle going. If you go with copper use this
http://www.amazon.com/gp/aw/d/B00025K0QC/ref=mp_s_a_1_1?qid=1419736917&sr=8-1

And you will need a test kit to test copper levels
http://www.amazon.com/gp/aw/d/B0002A5XGO/ref=mp_s_a_1_2?qid=1419736982&sr=8-2&pi=AC_SY200_QL40&dpPl=1&dpID=410jvSfViHL&ref=plSrch