Although cories in general are a bit salt sensitive it varies per species, on the other hand most do tolerate fairly high temps if the water is oxygenated well. This means you can use only 1 tsp/1 gallon and bump the temp to about 91F if you add a powerhead or an airstone or two, in most cases that will do the trick. Try to find out what species it is though. The Corydoras aeneus or bronze cory is one of the more common albinos sold and easily deals with the higher temps.