I have the heat lamp set up about 18 inches above the floor of the brooder and have covered the rest of the top so there's no cold air coming in, but it got REALLY cold here last night and this morning the temp in there was only a little above 80. The chicks are less than a week old. What should I be on t he lookout for in its caused problems for them? They all looked lively when I came in, and were eating and drinking normally. They weren't even all huddled up under the lamp. They all seem to pile up a few inches to the left of it. You think they're okay?