So far, I have looked at Petsmart and Feeders Supply for a 25 watt Marineland stealth visitherm and can't find any. They have the 50 watt and above but no 25 watts. Would a 50 watt possibly work in a 2.5 gallon if the heat is turned down or would that not be a good idea? I can't find the 25 watt anywhere online, except drsfosterandsmith and they are 25.99 plus shipping on top of that! Yikes!! That's a little more than I want to pay. I may just go to Walmart and get another Tetra whisper. Its working ok in Rusty's tank.