CHE not hot enough

[akane]

20 long.... that is not equal to a 55 at all given the massive height difference and you'll really heat things directly under a 100w while it's on with the short height which could be your problem that it's spot heating too much. A 100w should be more than enough. Especially if you hold some of the heat in the ends. I can get that in a 20long with a 50w bulb. I'd say there's a problem with how you are placing it and the probe or the thermostat. Like I said the spread might be so small with the height and the high wattage bulb you are spot heating directly under the bulb and shutting it off. Without a thermostat I could read 90F to half way across my tank, higher under the bulb, with the bulb shoved all the way to one edge and I don't even want that hot with like I said a 50w.