I have a visi-therm stealth 50 in my 10gal that I'm starting up. I had a 200 in a 50gal I had with no problems, and friends use stealth heaters with no problems. Mine had been running in a the 10gal for 24 hours. I have it set to 76, yet the tank water is 70 degrees. How long does it take to get 10 gallons of water up to temp?