I grow my javas in 82F...and they grow like mad in my 55g.
ditto. Though with the cooler weather I've gotten my temp back down to 77-78. My room generally stays warmer than the rest of the house so combines with heat from my PC lighting, and an 80*F room temp, my temps were about 81-82.5 and my java fern established itself fine. I will see if it grows faster now in cooler temps.