Hello all. I have a question concerning topping off. Here is the deal. I have just completed my second all grain batch. Since my first batch I have learned to compensate for grain absorption as well as loss of volume of boil. I have not yet figured out how to figure out loss from mash tun. Well anyway I hit my targets across the board. I ended up with 5.5 gals of 1.05 wort. YA ME! Well I decided to try and whirlpool and eliminate cold break and hop debris. When all said and done I ended up with just shy of 5 gals. Oh and I took my SG from the kettle before siphon into fermentation bucket. So finally the question. Should I have topped off to at least 5 gallons with clean sanitized water? It is fermenting great right now but could I do that now, day one of fermentation? Or is this a live and learn. My main concern is that when I transfer to secondary for dry hop I will have too much head space that could lead to too much oxygen exposure.