Suggestion. 86 degF and 2.5 tsp/gallon
If those sharks aren't too sensitive to salt, I would think a 2 tablespoons/5G would be more appropriate (if not even more). Also - may want to get another heater as most strains of Ich die at temps above 85F. All you're doing now is speeding up their life cycle and I don't think that salt content is nearly enough to kill the Ich.
If you increase the salt, do it slowly over a two day period and watch for stress.
I had pretty severe case of itch in 4 fishes in my new tank. Raising the temperature to 86 degF and slowly adding aquarium salt to 2.5 tsp per gallon caused the ich spots to disappear in 3 days and maintaining the same for 2 weeks has gotten rid of the ich in my tank.
Note: Just read up/ask if your fish can tolerate the temperature and salt. Also, after doing the above, watch your fish for signs of stress.
My goldfish, angels, swordtails, platys and mollys don't have any problem with the above treatment.
Also, I'd suggest not adding any new fish until you've eradicated the ich from your tank. Or else the newcomers will be also infected with it.
I would suggest using medications as a last resort because I've heard they can sometimes destroy the beneficial nitrifying bacteria in the tank.
Hope this helps.
aquamate