I put the new fishy (who still doesn't have a name :/) in my bedroom, which is a few degrees cooler than the rest of my house. I have my other two boys in my kitchen, where they stay at a nice 78-80 degrees (F) with no heaters.
The new boy's thermometer is reading 74 degrees (F) and he's acting chilly. Plus, when I put my hand in the water, I could feel that it was much too cold for him. I bought him this heater:
I rinsed it and put it in the tank with him before I left for work. When I first plugged it in, the indicator light turned red, like I expected it to - indicating that the water was too cold and the heater was actively working to warm it up. When I got home 6 hours later, the light was green, indicating that the water was the target temp, but the thermometer showed the temp hadn't changed at all. When I put my finger in the water, it was still cold, and the heater wasn't warm at all.
I went back to Petco and exchanged it for another of the same heater; I explained to them what had happened and they agreed with me that it must be a heater defect. I brought the new one home, put it in the tank and the same thing happened. The light is green, the water is cold, and my sickly fish is unhappy
Am I doing something wrong and missing it? Or did Tetra send out a lame batch of heaters?
Details: the tank in question is a 3 gallon acrylic cylinder shaped tank with an LED light, that is stone cold (the other boys' lights emit heat - I think they're incandescent or fluorescent?), and is unfiltered.
Thanks for any input you may have!