Help! ich in community tank

[ergaziturboman]

First thing first, here is my tank info:
1. Water parameters
a) 72 degree.
b) 7.8ph.
c) unknown
d) unknown
e) Ammonia 0, Nitrite 0.
f) 20%~30% weekly water change

2. Tank set up
a) 45 gallon community tank.
b) black sand.
c) tetrao HOB filter, rated for 30-60 gallon tank.
d) mediumly planted.
e) this tank has been setup for 4 months.

So I have 6 neon tetra, 2 rummy nose tetra, 2 oto and 9 cory habrosus. Just a few days ago, I introduce 7 emerald green corys. This morning I noticed there are small white dots on the tetras but I havn't noticed anything on corys. Right now I am planing to raise the temperature. But habrosus likes temperature on the "cool" end, to what temperature should I go? Are they able to withstand 82 or even 84 degree water? I don't plan to use any medication at the moment, but will try if things get worse.
What's your suggestions. Would like to hear from you guys.

[Coriequest]

I used fenbenzadole aka Safeguard dog wormer, a tweezer pinch for twenty gallons over three days once a day, dissolve it well in tank water first. Worked well. It's not very much powder. I've also heard divide the packet into one tenth portions and give one portion for three days. Did not harm any livestock including amano shrimp. Available at Petco, etc in dog section. Hate ick. Cories can take small amounts of aquarium salt, I did one teaspoon in a drip line for two or three days in my ten gallon hospital tank for a bacterial infection. Cories were fine,