Lightbulb watts vs Heat emitted

[ShadeTreeMech]

mmmmm.....cooked craaabbb......Of course I think his are a bit too small to eat easily

I think the OP said the bulbs he had weren't putting out quite enough heat.

[Ryland]

Originally Posted by Piwoslaw

Then what's the point of getting hotter bulbs???

The point is, if the 40 watt bulb was working most of the time and it's only really cold days and nights that he needs more heat then why risk over heating them? or waste the energy? a thermostat set at 110 degrees or whatever would keep them from cooking, otherwise you need to keep a stock of light bulbs on hand and change them every few days/weeks in the spring and fall.

[RobertSmalls]

Just bury the aquarium like so and let the crabs heat themselves:

[ShadeTreeMech]

want a bit of water heater for the insulation????

Wow, that is nicely done!!!! Why didn't the top get covered? It looks to be electric, so no harm in it. Or was it removed for the sake of the photo?

[IsaacCarlson]

I think that is a flue on top...might be gas? Might be insulated good enough that it uses only the pilot light and would not need venting.

[RobertSmalls]

IWillTry.org Super insulate your hot water tank

If this heater weren't already converted to electric, you'd need to leave both the top and bottom open to airflow. However, he did finish the job with insulation right up to the top of the plywood box.

Remember, anything worth insulating is worth superinsulating.

[IWillTry]

Hi. Crazy hot water tank insulating guy here. You may be interested to know that the above hot water tank only requires about 65W on average to keep the water at 45 degrees C for showers each morning. It could literally be heated with a light bulb but I use a 520W element and just run it 3 hours each morning on a timer.

A couple points of interest related to the crab tank discussion:
1. The efficiency of any kind of light bulb as a heater can be considered very nearly 100%. With an incandescent bulb you might get around 95% heat and 5% light "at the bulb" but the light will be converted to heat when it is absorbed by a surface. A 20W fluorescent bulb or a 20W incandescent bulb or a 20W anything will all put exactly 20W of heat into a closed container if you don't let any of the light escape. That's the law of conservation of energy.
2. Temperature rise (difference between internal temperature and ambient temperature) is proportional to power (Watts). So if your tank gets 10 degrees warmer than the room when you use a 40W bulb, it should get 15 degrees warmer than the room with a 60W bulb or 25 degrees warmer than the room with a 100W bulb.
3. If you're starting from zero insulation, adding a little insulation will go a long way. Even just some cardboard taped to the sides of the tank could raise the temperature enough.

Good luck.

[Piwoslaw]

Instead of replacing the light bulb with a more powerful one, what about adding a second low-watt bulb at the other end of the tank? That way the heat is distributed much better, instead of a single hot heat source which could potentially be hazardous.