Beer Forum

I was high on my gravity. Really high. The target OG was 1.035 and I ended up with 1.050. Maybe someone has some kind of idea, because I really think the brew day went pretty normal...

Here's the notes and recipe:

I don't remember who's recipe this is, but I got it off the AHA website after hearing about it on an old episode of the Session. It's a Cherrywood Smoked Mild (or supposed to be a mild)

4 lbs Maris Otter
3 lbs cherrywood smoked malt
0.50 lbs crystal 60L
0.25 lbs chocolate malt
.050 lbs Munich

.35 oz fuggle (60 min)
.12 oz challenger (30 min)

I missed my strike water temp. I was shooting for 152, but got 148 so I let it ride. I mashed in a 5 gal cooler for 60 min, tried to hit 168 with the top off, but only got to 150. Ran my first runnings and then batch sparged with 170 degree water.

My pre boil volume was about 6.25-6.5 gallons and I lost about a gallon with boil off. Other than missing my temps, I didn't think anything else seemed wrong. It was a 60 min boil without issue, added whirlfloc and yeast nutrient, chilled and pitched as usual...Any ideas why my gravity would be so high?

Do you know what efficiency and batch size the recipe was stated for?

If they called for 6 gallons post boil, for example, at 70% efficiency, and you ended up with 5 gallons post boil and hit 76% efficiency then you most definitely would see an increase in gravity.

Batch size was slated for (on original recipe) 6.11 gallons preboil and 5.5 gallons following a 60 min boil with 10% evap loss at 69% efficiency.

I don't know exactly what my efficiency was because its a new system with only two brews on it so far.

I ran the numbers, and using those volumes your extract potential was 1.051, and you should have hit 1.038 at 75% efficiency. There's a couple of reasons you might have gotten a 1.050 OG:

1. Your efficiency was actually 100%, or the brew fairy smiled (both highly unlikely).
2. Your balance is way off, or somebody nudged your elbow when you were weighing grain (more common).
3. Your hydrometer is defective (check against distilled water at 16C).
4. You neglected to account for the 4% shrinkage of wort when cooling from boiling to pitching temps (but this has a relatively minor effect).

It may be a combination of one or more of these factors. Let us know what you find out.

Charlie

A 10% evap rate seems like a pretty low estimate (unless you've calibrated your system there, but it doesn't sound like you have). Same with the efficiency. Those combined with a low mash would raise your gravity significantly.

Also make sure everything is calibrated - scales, thermometer, hydrometer, volumes. I stress that part because you said that your pre-boil was about 6.25-6.5 & you lost about a gallon. You shouldn't be guessing on those things if you want to be hitting numbers repeatedly.

Ozwald wrote:A 10% evap rate seems like a pretty low estimate (unless you've calibrated your system there, but it doesn't sound like you have). Same with the efficiency. Those combined with a low mash would raise your gravity significantly.

At 75% efficiency (a common figure) a final volume of 4.2 gallons would more or less exactly reproduce your results. Could your final volume have gone that low?

I mention the hydrometer because some monkey snuck in the lab one day and cracked the tip of my 0-8.5 P saccharometer. I took an FG on a pale lager, got 7.2 P, and was having a serious WTF moment until I noticed that there was liquid in the bulb.

+1 on determining your evaporation rate. Mine hovers around 1.15 to 1.25 gal/hr depending on ambient temperature and humidity.

Charlie

Well, I've got another brew or two this weekend to help me determine my efficiency. I'm sure that was the problem, or something as simple. I've since kegged the beer. It finished at 1.010. I'm a little disappointed because it doesn't have the body I want. It's almost watery. But out of the last five, it's the only one I haven't been really satisfied with. I'm going to brew this again and see if I can dial it in.

Let us know how the efficiency goes next brew. Curious to hear if it was just a one-time thing.