Melissa said:
The red discharge is normal, but excessive amounts of it can be a sign of URI (upper respitory infection). All rats carry a disease called "mycoplasma" and many things can make it flare up. It would be a good idea to search the forums for "Myco" and read up on it. There is also the "new home sneezes" that most rats seem to get. It usually clears up in a few days.
Try looking on craigslist or other classified for a wire cage if at all possible, you're right in thinking that she needs a wire cage for ventilation. Kept in the aquarium I'd guess she'll be more prone to a myco flare up. Once they get a myco flare up you -must- take them to a vet for antibiotics. I can understand the financial burdens all too well (we're currently struggling through a death in the family that led to a probate issue, which led to a bankruptcy issue, which led to a foreclosure issue, etc etc) I found a great 4 story wire cage from the local Goodwill shop for $25!
I would suggest getting her on some sort of solid foods also, some lab blocks preferably (usually have to be ordered online, very cheap though, few dollars for a large bag). Tek-Harland (I think!!) is the brand, I buy mine from 'thecraftyrat.com' but there are dozens of places to buy them.
Possibly a nice LOW protein dog food, preferably an organic or holistic brand (nothing you'd buy at the local grocery store, that's for sure).
Fresh veggies everyday are good, I'd limit the fruit to just a few times a week, not everyday. Do a search for "forbidden foods for rats" and you'll see a good list of what not to feed and why.
Good luck and enjoy your ratty!! (and get her a cagemate very soon! a lonely rat is a sad rat, even if you spend an hour a day with her there are 23 lonely hours passing by, even 6 hours of human contact a day cannot make up for even one hour of rat companionship).
EDIT: The Lab Blocks are called "Harlan Teklad 2014 Vegetarian Rodent Diet" and "Harlan Teklad 2018 Vegetarian Rodent Diet". One is for youing/pregnant/nursing rats and the other is for older (8 months and up) rats.