SG is always low

[bobrap]

Another thread on low SG. My last four batches have all been way off the mark. I us a 10 gallon cooler for my mash tun. I have tried following the AHS recipes to the letter and what I got from beer smith. I try for about 20 degrees over the recommend mash temp for my strike water? I recirculate, drain the tun and then add the recommended amount of 175 degree water. Wait about 20 min and then recirculate again. 5 gal all-grain. Any suggestions or help is appreciated.

Example- did a hefeweizen today with a projected OG 1.050. My pre-boil was 1.028.

Or...should I just not worry about the numbers and just make it

Thanks for any guidance.

 

[dbreienrk1]

What temp are you mashing at and for how long? How much heat loss does your system have? Are you sure you temperature measurements are correct? What is your grain bill? I think you are batch sparging, correct?

 

[nebben]

What does your grain crush look like? 1.028 is incredibly low. I also wonder if you could describe more about how you are sparging? Are you leaving any wort in the tun? Knowing how long you are mashing would also be good to know.

 

[FastTalker]

You are probably not as far off as you think. OG usually refers to the post-boil gravity (or pitching gravity) not your pre-boil gravity (extraction gravity). You SG will be higher after the boil.

Are you doing a correction for temperature when you take you measurement? Most hydrometers are calibrated for 60 degF. Your measurement will be lower than the actually SG.

Here's a conversion tool.
http://dd26943.com/davesdreaded/tools/convert.htm

1.028 @ 140 degF is corrected to 1.044.

 

[TipsyDragon]

Show us a picture of the inside of your mash tun.

 

[bobrap]

Thanks for the help guys. My mash temp is 150. The inside of my mash tun has a braid in the bottom (round cooler). I drain as much liquid as will come out before I add more water. Didn't mention, I mash for about 75 min. Grain crush looks ok to me (not that really means anything ). My post boil gravity today was 1.050. But, I added dme and alcohol boost. My readings are taken with a refractor enter. I'd like to get as close to the numbers as I can without becoming OCD about it.

 

[duboman]

Couple things, your mash water volumes need to be spot on or you are diluting the wort which will drop your gravity, in addition how's the crush? I had an issue on a few batches and I spoke with my LHBS dude about it, he re-calibrated his mill as I don't have one yet and since then my efficiency went back up and now my numbers are spot on.

You can also try a longer boil I concentrate the wort more, you'll get less beer but it will be what you expect

 

[tgmartin000]

What were your mash and sparge volumes? Are you running off all your sparge water? Do you stir the mash or sparge? Grain bed temp during sparge? 175 sparge water might not be hot enough. I use 185, single batch sparge.

 

[nebben]

A couple of things are coming to mind with this. First, make sure that your refractometer is calibrated properly. It should read 1.000 or 0 brix when using room temperature distilled water. Also, you should take a sample with a hydrometer and record the difference between that and your refractometer in order to figure out if any correction is necessary.

My refractometer was off significantly, which was a surprise to me. It turns out not all refractometers are created equal, and some don't measure wort as well as others.

Also, don't ever trust any conversion charts for hydrometers over 100F. Things get wild above that temperature.

I am a big fan of stirring up the grainbed each time I add sparge water, doing the vorlauf, and draining. Not stirring could have an impact.

Ultimately, I think that your measurement may not have been accurate if you're just using a refractometer.

 

[helibrewer]

What is your first run gravity? Comparing this to the max theoretical will give you your mash efficiency...from there you will be able to start nailing down where things are going pair shaped.