I've recently began all-grain brewing. I have encountered two problems in my new endeavor. 1. I achieve boil over every time (4 batches of 5 gallon) no matter what I do. 2. My final wort volume after boil is almost always 3 gallons. My questions are thus - what can I do to prevent the boil over? I have sat and blowed on the wort till I get a sore throat and turned the heat down. Also, is it o.k. to add water after racking to the fermenter. When I brewed exclusively with extract, adding water after the boil was the norm. What issues would I have with adding water? Thanks for your response.

Put a few drops of antifoam in your kettle.

I've noticed that adding First Wort Hops drastically reduces the hot break for the remainder of the boil, and thus reduces the potential for boil overs. I don't know if others have had similar results, but that's my experience.

Keep a spray bottle of starsan handy, when it starts to get near the top of the kettle.. spray it.