What the hell just happened?

I'm brewing https://www.homebrewtalk.com/f71/austin-homebrews-belgian-white-beer-135187/ right now, hit my mash temp right on, sat it for an hour, sparged and filled the pot.

The wort looks very light in color compared to anything I've brewed before, my pre-boil gravity is like 1.020, what the eff just happened and what should I do about it?

My guess is that your temp is about 130-140, right? You're probably fine. You need to adjust for temperature and boiloff, both of which will give a more accurate reading.

OK first off what temp did you take the reading at? Higher temperatures will read lower on a hydrometer and you cannot really trust the readings. If you used a refractometer, did you calibrate it first?

Second, pre-boil gravity is going to be lower than final gravity, because you boil off volume. What are the preboil volume and target final volume?

Third, are you sure you got all the wort you can out of your MLT? Even another 1/2 gallon of wort in the MLT is going to make a difference in your gravity.

Here is a good calc. for determining you OG and FG allowing you to enter the temp and reading.
http://dd26943.com/davesdreaded/tools/convert.htm

could have been as hot at 150F when I took the reading, I know that does account for some points, I'm only about .5-1gal over my target volume. The wort just "feels" thin.

thanks for the calculator, it looks like I could actually be more around 1.038 with the temp difference, but thats still .01 off from where I want to be, AHH first brewing disaster yet!

This calculator isn't bad. Otherwise Beersmith or Promash will help a lot for things like this, but they cost $.

Ok, given that data, do nothing. Corrected for temp, your pre-boil gravity is 1.039. If you boil off a gallon, you'll be at 1.043 into the fermenter (assuming a 5 gallon batch).

gtpro said:

could have been as hot at 150F when I took the reading, I know that does account for some points, I'm only about .5-1gal over my target volume. The wort just "feels" thin.

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SOME points? try 19! If you were at 1.020 at 150f, your actually at 1.039. I call panicky pete on you.

Assuming you have a 5 gallon final batch size and 1 gallon of boiloff (so six gallons as of measurement) then you're right on by my math.

.01 wont be that big of a deal, and according to the cal it appears your gonna have about 5.1% alcohol. Id say the color wont matter after a few of these are down the hatch +)

gtpro said:

thanks for the calculator, it looks like I could actually be more around 1.038 with the temp difference, but thats still .01 off from where I want to be, AHH first brewing disaster yet!

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.01 off and you're worried? That's nothing. Also, when you boil off for an hour, your volume will go down and gravity will go up. Promise.

Ok I just took a reading of 1.014 at 185F, according to the calculator I'm at like 1.046 pre-boil, thats very reassuring, thanks a lot for the speedy responses guys! I was 2 seconds away from racing down tot he HBS to pick up some DME.

Ya know, I watch all these other noobs on here freaking out over nothing all the time, never thought I would be one myself

The 1.038 is a pre-boil gravity right? When you say you are .01 off, its looks like you are comparing it to the OG (post-boil) gravity reading. You lose volume with boiling, so 1.038 may end up being 1.048 post-boil.

We have some decimal errors here. Let's be clear:

0.100 difference is a lot to worry about.

0.010 difference is significant, but I'll just let it ferment out. I'll try to pinpoint my losses so I can improve the process for next time.

0.001 difference is negligible.

Also, dropping your hydrometer into hot wort is a fantastic way to shatter it. Cool your samples in the freezer or in an icebath. Not only will the readings be more accurate, but your hydrometer will thank you. Consider getting a refractometer, which only takes a drop of wort for each reading.

Well, brew is over, got a final OG of about 1.043. Missed my mark by a touch, this one will be a quaffer. Every brew is a learning experience thats what I say!