Also, what are the floor dimensions of your tubs and the dimensions of your heaters? I would be cautious about using a heat lamp over your tubs. You would need to make sure it was very stable so that it wouldn't come into contact with the lid and you would also need to control it with a rheostat to reduce the possibility of melting the plastic. You might also look at the possibilty of using a space heater to raise the temp in the whole room...