The important bit you need to know is your efficiency. This is how effective your brew gear and your techniques are at extracting the good stuff out of the grain and into your boiler.
Do an easy pale ale, 100% pale ale malt, aim for a final 1.045 og into the fermenter. Then, use whatever quantity of pale ale grain you had as the starting point for working out your brewhaus efficiency. You can then be all technical and start plugging stuff into brewing software, or, go the simple path and say, "I had 5kg of grain, this gave me a starting gravity of 1.048 in the fermenter before I pitched my yeast, next time I want a 1.040 brew I can use x amount of grain."
Do not worry about what efficiency other people achieve. This often seems to end up as a competition as to who can urinate the highest up the wall. After 10-20 brews, by all means start comparing your efficiency to other brewers. This may highlight a problem you have with your techniques. Many recipes assume that you have 75% efficiency, just scale everything for your brew. The important point is to aim for what your brewery achieves, not what some pencil pushing 1000 all grain brews book writer achieves with their tuned setup.
The temperature conversions of sg can be very hit and miss. Take your sample, put it in a plastic bag, cool it to 20 deg in an ice bath, then do your hydrometer reading.
Some people use the amount of tannins in the runoff as to when to stop sparging. As you get near your expected cutoff point, run about 3 mouthfuls of the wort into a coffee cup (this has a large thermal mass and cools it quickly.) Taste it. Run some off and chill it, take an sg reading. You will soon start picking by taste when to stop sparging. Some people pick this point easier than others. Do not do this when drinking coke, or coffee or beer, this will make your tastebuds less attuned. Do not aim for the sweetness level. The sugars being extracted late in the sparge are the longer chain sugars and do not taste as "sweet" as the shorter chain sugars.
I find I can smell a change in the wort runoff and stop then. A refractometer also makes this step easy.
I do not recommend just sparging till you reach the required volume. If everything is not right, you WILL be sparging tannins into your brew. It is better to go a bit low on expected sg, rather than sparging that extra few points.
Thanks for activating an old thread rather than starting a fresh thread. These questions are very important to have a good background, rather than launching into a new thread and just repeating old stuff.
