Why is my gravity so low?

This past weekend I brewed a Pilsner. I used 7.5 lb of LD Carlson Pilsen Light DME for 6g of water. If you assume 42 gravity points per lb per gal the OG should have been 1.0525, but my gravity turned out to be 1.042.

What could have gone wrong?

I have had problems with low OG before, but I assumed I put in too much water to the fermenter and this time I was sure the ratios would be correct, but the OG was low again.

Gregg

 

What was your final volume? I am assuming the 6 gallons was measured preboil?

With 6 gallons final volume, and 7.5 lbs pilsner dme, I'm getting an OG of about 1.045. The pilsner dme in my brewing software is 36 points.

 

Did you stir well after adding the water?

 

It's a pretty common issue for ANYONE topping off with water in the fermenter (and that includes partial mashes, extract or all grain revcipes) to have an error in reading the OG...In fact, it is actually nearly impossible to mix the wort and the top off water in a way to get an accurate OG reading...

Brewers get a low reading if they get more of the top off water than the wort, conversely they get a higher number if they grabbed more of the extract than the top off water in their sample.

When I am doing an extract with grain recipe I make sure to stir for a minimum of 5 minutes (whipping up a froth to aerate as well) before I draw a grav sample and pitch my yeast....It really is an effort to integrate the wort with the top off water...This is a fairly common new brewer issue we get on here...unless you under or over topped off or the final volume for the kit was 5 gallons and you topped off to 5.5, then the issue, sorry to say, is "operator error"

If your target volume was correct, then it will be fine.

More than likely your true OG is really what it's supposed to be. And it will mix itself fine during fermentation.

 

I did the same exact thing last night. I just breathed the biggest sigh of relief. Good thing to i was about to pass out.

 

I have not thoroughly stirred before and gotten a low OG reading.

 

your software is wrong then. LME is usually 35-36 ppg, DME is around 42-45

 

Thanks for the replies, and advice.

I put the wort into a glass carboy and stirring is a little harder there.
Guess next time at the brew store I'll invest in a stirrer/ aerator for the drill.

Guess I find out how things went in a couple weeks when racking into the secondary.