85*F is actually better to put them temperature at, as it will help kill those icky little things. You will want to do that in the home tank too, as most likely if you see ick on your fish, the eggs have been dropping and you have them currently in the home tank. It is very contagious.
Now, I would look into Methane Blue
before you use it.. as it is quite harsh. Generally used for superficial fungus infections, so it won't really be doing much for your ick problem.
The best treatments for ick is:
Raise temperature to 85 F, and then it depends on how you want to go about treating.. you don't want to use AQ salts with medications, so it's an either/or situation..
For salt, add 1 tsp/gal Aquarium Salt 3 times, 12 hours apart so that you end up with 3 times the normal concentration. Perform daily 100% water changes to remove fallen parasites before they can reproduce. Replace the water with the right amount of salt. Do not continue this treatment for more than 14 days.
If it fails or you do not want to use salt, treat with Jungle’s Parasite Clear, API Super Ick Cure, or Kordon Rid Ich Plus.
On a side note, keep in mind the water will be cooler then the outside temp.. what you are wanting to avoid is temp fluctuations, which you get without a heater. Yes, your tank may be in the healthy range, but if it gets cooler at night then you are risking the temp fluctuating too quickly which could easily put your fish into unreversable shock- why the recommendation of a heater, as it will keep the temp steady.