... A year after getting my first T I finally got a heat lamp and temp gauge. Here in the Midwest it’s easy to keep my house at 68-70 during the winter, but I’ve had a small space heater that I keep more than a foot away from the T’s. For the last year I did the best with what I had; I would consistently check the glass to make sure it never got too hot. Not sure why it took so long for me to get a better setup but my T’s are definitely more active (which I take for “happy” ). Lesson learned and grateful for everything I’m learning on this forum!...
The 50s would be the bottom range on a tropical species. I've seen A. Seemanni on vacation in Costa Rica hunting at night in that temperature range.If you are flexible with your room temps, try getting it to 75 degrees. 60s and low 70s are at the bottom range for tropical species. Think about what the climate is like at the equator, either desert or jungle as the case may be.
If the room is to cold and you must use a heat lamp, in my opinion, keep the light bulb more then 8" away from anywhere the tarantula can touch and not more powerful then 25 watts. Mount it to the side or above, never below or inside!!
You will need a voltage controller switch unless you user exact distance to get the temps right. You will also need a point and shoot Infrared thermometer to check every square inch for unsafe areas that can harm the T.
If this doesn't sound like fun, just do mid 70s in your room and be happy. Always avoid all direct sunlight as well.