what breed are they? tbh I don't think the ecoglows are always warm enough for the first few days on their own, especially if chicks are tiny (mine are all large fowl). If its the smaller one in particular its not heating up a great deal of space. I used to put a ceramic bulb in as well so that increased the ambient heat a bit in the brooder. Once they are about a week old, chicks are quite hot, sweaty little things that tend to spend more time on top of the glow than under it anyway but it still pays to not subject them to large fluctuations in temp-a broody hen wont let them out from her very long at all for the first week or two, unless its very warm.
I've got a more adjustable one now-built for 25 chicks I think, with 14 under it.