Originally Posted by GreenTerror
I think my problem was that my stove top and patience level were too low for the first try and I really didn't get the vigorous boil needed. I think if more brewing is in my future I'll need to look into a propane burner. Plus then I can do it in the garage and make the wife happier
While a vigorous boil is important I'm not sure this would cause this problem since you are boiling off water and then topping back off. If you start with five gallons at, say, 1.050 and boil it down to four gallons you would have about 1.0625. If you then top off back to five gallons you bring it back to 1.050. I guess it could be the amount you topped off with. For example, if you have the same 1.050, but four gallons and top it off to five gallons you'd drop to 1.040. If you had topped off with less water you'd have a higher gravity, but if you followed the instructions this is unlikely. I think the guys pointing to the mixing might be right. You have two liquids with different specific gravities (water and your wort) going into the same container. It takes time for them to blend fully. This is the science behind the "Black and Tan"--two liquids of differing specific gravities can be layered temporarily.