I'm looking forward to getting 20-30 chicks but I dont own a heat lamp. Last time i had chicks they were 8 fluffy balls who thrived just fine under a 30 W incandescent light. I am going to keep them inside where the temp. is 70 degrees the first three weeks, do you suppose 30 W will be enough? Will they be able to "warm each other", so to speak, because of their number?