Didn't hit OG

Just made my first PM brew. While trying to pay attention to the details of a new process I didn't bring the post sparge water to a full boil before adding the DME. It took a 1/2 hr to get the 5 gal to a full boil. Recipe OG is 1.065. Measured OG is 1.050. Think not bringing water to a full boil before adding DME was the major cause of not hitting the recipe OG. Have not calculated efficiency but that could be another factor. Any thoughts on where else I went wrong?

The sugars in the DME should have dissolve just fine in your water as long is it wasn't ice cold. And if they didn't dissolve you would have seen it at the bottom of the pot.

I think it's more likely you have had poor extract efficiency, or possibly your SG readings are off; did you compensate for the temp when taking the readings?

The OG of 1.050 was taken after wort was cooled to 70F in primary bucket. The gravity of the post sparge water was 1.028 but did not compensate for temp. Did not measure temp but think was somewhere around 140F as sparge water was 155F. How can temp be compensated for?

The DME did dissolve and water temp in brew pot was about 140F or so as noted above.

I had a formula for calculating efficiency but can't find it now. Searched for a formula for calculating efficiency but most postings are theoretical discussions on efficiency and not the formula.

Think the formula involves adding up the PPG for each grain, subtracting your measured post sparge gravity and either multiplying or dividing by the amount of post sparge water collected. Please let me know if I am even close on this one.

Another though I had: did you hit your target volume? If you didn't boil it down as far as expected you'd have more of a weaker wort.

here is a SG temp calculator In my experience the 140deg sample will cool down to about 128-135 by the time you actually get a reading. In the future stick a little thermometer in your hydrometer tube to get a more accurate temp.

You've got the basic idea of calculating efficiency. There are charts and online calculators out there, but off the top of my head; 2 row base malt = 37 pt, crystals are more like 32, and darker roasts are as low as 25. On second though, those numbers may be quite inaccurate, you should look it up.
But yes, add all the possible points. Then take your temp compensated SG (I'd guess about 1.042), and multiply that by the amount of water you have (in gal). Then divide that by the potential points.

Efficiency formula:

SG x SWG (SG=Sparge Gravity, SWG=Sparge Water in Gallons)
----------
PPG (Points assigned to grain in Hopville recipe)

SG=1.042 (temp adj) X 4 (gal collected)
----------------------------- = 2.2% efficiency!!!
186 (added total PPG from Hopville recipe)

Recipe PPG
6# American Two-row Pale 37
2.5# Ex. Light DME 44
1# Crystal 15L 34
12oz Munich Malt 37
4oz Crystal 40L 34
----
186

If calculations are correct the efficiency was only 2.2%. Something must be wrong, otherwise the beer contains about 0% sugars from the malt!!

ImperialStout said:

Efficiency formula:

SG x SWG (SG=Sparge Gravity, SWG=Sparge Water in Gallons)
----------
PPG (Points assigned to grain in Hopville recipe)

SG=1.042 (temp adj) X 4 (gal collected)
----------------------------- = 2.2% efficiency!!!
186 (added total PPG from Hopville recipe)

Recipe PPG
6# American Two-row Pale 37
2.5# Ex. Light DME 44
1# Crystal 15L 34
12oz Munich Malt 37
4oz Crystal 40L 34
----
186

If calculations are correct the efficiency was only 2.2%. Something must be wrong, otherwise the beer contains about 0% sugars from the malt!!

Click to expand...

you only used 2.5 pounds of extract? And hit 1.050? In five gallons?

Keep in mind that any hydrometer reading taken over about 90 degrees is useless- as they are notoriously inaccurate. Next time, cool the sample to under 100d degrees in the freezer or a pitcher of ice water, and THEN use the correction tables.

what was your batch size you took the OG from?

Yooper, Recipe has 2.5 pounds of DME and 8 pounds of grain. Post sparge water was about 140 - 145 deg F. Did not measure but starting temp of sparge water was 155F and estimated heat loss. Did not know to take sample of post sparge water and cool for an accurate gravity. Will do next time.

Dr. J, batch size, after topping off, was 5 gal. Post sparge water collected was 4 gal.

Another post I found said to calculate each grain individually and add the results.

Formula: grain weight x PPG/post sparge water

Example: 6 (pounds 2 row) x 37 (ppg) / 4 (gal collected) = 55.5

If you do the math for all grains and DME, add them together you get 99.97 (100%)

That is not right either. I know I am missing something

Okay so 5gal *1.050= 250pt
The 2.5lb of DME * 44pt = 110pt
250-110=140pt from the grain
140/total 8lb or grain = average of 13.75 points per lb.
That's a cruder way of calculating, but getting 30 pt pre lb is a normal number to shoot for.
The 30 number is at the high end of what a home brewer can get (aprox 80-85% depending on the bill), but is possible. But this shows that your extraction was rather poor.

Thanks for the help. LHBS says efficiency was 51% and problem seems to be water hardness. Have started a new thread on water treatment.