preboil gravity and efficiency problems

I have brewed 4 all grain batches so far and everyone seems to have a very low preboil gravity and different efficiencies. i typically mash for 60 min at 152-154 and i do a single sparge sometimes with a mash out. My sparge temperatures have been lower than i want them (around 162-165). Here is an example of my batch last night. preboil gravity:1.034 target:1.045
original gravity: 1.048 target: 1.053
It seems to me that all my preboil gravities are very low and the original gravity comes out low but a lot closer. My efficiency has also been all over the place, ranging from 58-76%. I am basically trying to get a efficiency so I can account for that when buying grains, but every batch seems to be a lot different. I take my preboil hydrometer readings at around 150 degrees and then correct them with beer alchemy. The one area I have been fairly consistent is with my volumes of wort collected. What do you guys make of this? Thanks!

Try sparging more, two times instead of just one. I find this leads to lower efficiency. More sparges means more rinsing of the sugars, which goes into your wort.

I also sparge with hotter water, in the 180 range. However, there are people on here that will advocate that sparge temp does not matter. This tidbit will be yours to decide if you think it matters. But, number of sparges DOES affect your wort. I don't think the gains are as much after 3 or 4 sparges, so 2 should be fine.

I consistently get about 83% efficiency with my system and technique.

Your grain crush can also be a culprit. Who mills your grains?

Your pre-boil and post-boil gravities should stay in line as long as you have your evaporation rate figured out, and that the Prue-boil wort is mixed very well prior to taking a sample. so 6.5 gals pre-boil at 1.034 then an evaporation rate of a little over 1.5 gals an hour would land you with the 1.045 you saw.

As far as numbers going all over the place.. What are you using or doing different between these batches.
To get some good numbers to work with, you need to make sure the volumes are accurate and mixed well. Your hydrometer is accurate, and your thermometer is accurate. and you are doing the same process like sparge done with no mash out, or with mash out
on every batch at first.

If you are doing paler brews, and your numbers are low compared to when doing darker malts, water chemistry, Ph, can be playing a part.

If you are buying kits from different sources of the same type, it may be milling and malt quality issues.

My suggestion would be to brew the same style brew from the same source a few times.

Check your thermometer for accuracy
Check your mash Ph (10-15 minutes in), then your mixed pre-boil Ph. (these are checked with a room temperature sample, so cool your sample down, then take the Ph reading.

When using a hydrometer, your sample needs to be below 100*F if using the temperature correction chart, or at the calibrated temperature written on your hydrometer.
The thermometer and hydrometer should both be in the solution at the same time so you have an accurate reading.
You always spin your hydrometer in the solution prior to taking the reading to make sure no air is trapped on the bottom causing a false reading.

Usually 60 minutes after dough in is enough time to convert a normal mash @ 152*F. Take the grain-bed temperature by probing different areas half way through the depth(center) of the bed about 5-10 minutes after dough in has been completed. This will tell you if your grain-bed temp is even through-out (no hot or cold spots)

You can always check for conversion after the hour with some iodine if you have doubts? (Read JP's how to brew on line for more details.)

Use around 1.25 quarts water per pound of grist ratio for your mash at first. water wants to be filtered.
Do your sparge the same way every time at first to get those numbers close to each batch. Once you get consistency, then you can try different changes in the process to see if it improves, or gets worst, but you have to try one thing at a time, once you are brewing with some sense of consistency.

What you want to do is get your numbers to fall into a area with consistency. Once you have that, then try different type malts and see if you get changes in your efficiency

I would say to cool your pre-boil sample to 60 degrees, or whatever your hydrometer is calibrated to, to take a reading. Everyone I've seen that took a reading with the temp really high and correct it using the formula or software has had not so accurate readings.

Thanks. I will try to keep the variables fixed on everything (like same grain crush, same sparge temps, same mash temps, etc.) and see if I get consistent results. I will also cool my hydrometer samples instead of using temp correction.

+1 on cooling the sample to 60F - throw the sample in the freezer if it'll fit (or fridge) and the temp will come down fast (just don't leave it in there too long!).

Yep, those temperature correction charts are worthless over about 90 degrees. I chill the sample (in an ice bath pitcher is fine) and then check the gravity, and use the temperature correction feature. I don't know why, but any sample over 90 degrees isn't even close to accurate, but under 90 degrees or so seems to be (with the temperature correction, of course).

If your pre-boil gravities are all over the place, but your OG is closer, and your boil off rate is consistent, this would seem to indicate that your pre-boil gravity measurements are wrong. This could be caused by testing at too high a temperature, but could also be caused by not mixing the wort sufficiently prior to drawing off your sample.
One other thing, do you stir the sparge water with the grains really well. With a batch sparge, the stirring is what dissolves much of the sugars. If you don't stir enough, you will get low gravities.

-a.

Three quick things that can improve effificiency (but there is a lot more)

• Grain crush - maybe the biggest
• Increasing sparge temps
• PH of water

Also, as previous poster said, two batch sparges are better than one. Another thing to consider is to stir your batch sparge mash and let sit for 10 minutes or so before you run off.


Good luck! You'll get it nailed down soon I would bet.

What temp of the water do you guys use for 2 sparges? I use a 10 gallon rubbermaid cooler with a false bottom and just dump the water from my boiling pot into the cooler. I do not use a hlt. I have tried 175, 180, and 185 and the highest temp my grain bed got was about 165. Also since I will be doing 2 sparges, the water will probably have to be even hotter, atleast for the first sparge. Thanks.