Change in OG

[mic]

I hope this sounds familiar to you seasoned veterans out there. I am an extract brewer and I use 6 gallons of water for my boil. I always have to add water to my carboy to reach 5 gallons due to evaporation during the boil. I decided to start with 6.5 gallons on my latest batch to solve this problem.

My question is, does using more water effect my OG? My OG was a bit lower than I expected and I know other factors can cause this but I did not know if the amount of water in the boil can effect it. Thanks.

[Tweek]

yeah it will. Gravity is the reading of sugars in the water. so naturally the more water you ahve the lower your og will be.

[S.F.B.]

Your OG should come out about the same unless you ended up with more than 5 gal at the end of the boil. Whether you top up to 5 or boil down to five should make no difference.

[shughes600]

A helpful tip here is to measure the gravity at the begiining of the boil. Calibrate your brewpot in some way so you can measure the amount of liquid in the pot. I use a stick that is taped off at certain points which I insert to the surface of the liquid. The tape mark shown at the top is my volume in the kettle.

The procedure that follows exploits the fact that the gravity is telling you the amount of sugar dissolved in the water. This mass of sugar will not change during the boil. Adding a gollon of distilled water will lower your gravity by dillution. The goal is to hit final gravity accurately. Multiply final volume by the intended gravity numbers after the decimal. Example: OG 1.048 Volume 6 yields 288. Compare this to what is in the kettle. 7 gallons at 1.037 yields 259. The wort needs more sugar. You have two choices, add DME or boil longer till 1.048 times X gallons = 259. DME adds 1.045 (45) per pound so in this case add 6.5 ounces or so. If you have too much gravity either dillute or make a bigger batch. Doing this at the boil time allow you a lot more time for correction and insures all of the wort was boiled together. It's kind of hard to add DME directly tot he carboy.

Sorry, a few homebrews and the hour might have made my explanation of that trick a little hard to follow.

[mic]

Thanks for the info. I'll just keep experimenting which is the fun in homebrewing.