Beginner OG question

It's not "bad" but you will have lower alcohol, hop utilization, and final gravity. You'll still have beer, just not the beer you thought you were brewing.

 

New brewers regularly post about lower than expected OGs. A couple of things to be aware of:

If extract brewing it is imperative to give a very thorough stirring after any top-off. Otherwise it's easy to come away with an inaccurate number.

You really should calibrate your hydrometer. Most are set up for 60°F . . . give yours a test in tap water at this temp and see what it reads.

Hydrometer readings are temp dependent, search Google for a conversion chart. Usually the reading of your sample has to be adjusted for current temp.

If indeed you finished 20 points below target, then this reflects poor efficiency. Nothing fatal here . . . just an area for improvement.

 

Without seeing your recipe and knowing what your brewing procedures were, it's hard to pinpoint why you experienced this low OG. Everything suggested in the above posts points to just about all of the possibilities that could be the cause, with the top-off water not being mixed very well before taking your gravity reading being my first guess (assuming you did an extract brew and needed top-off water).

However, I am wondering if your 6-gallon recipe was actually designed for 6 gallons, which to me is not a normal batch size, and possibly you modified a 5-gallon recipe to try to get more beer from your brewing session? Or did you follow the recipe for a full-boil 5-gallon batch which said to start with 6.5 gallons, but with the expectation of 1.5 gallons boiling off so that you end up with 5 gallons, but only a half gallon was lost? Just a couple shots in the dark as additional possibilities.

If you get it figured out be sure to let us know so that we can do some strutting and cluck-clucking around our boil pots.

 

If you are extract brewing, efficiency isn't a problem. You either messed up and over-diluted (unlikely), messed up and didn't use all the extract (unlikely), messed up and misread or otherwise misused your hydrometer, or messed up and did not draw a well mixed sample for your hydrometer test. It happens.

 

If the volume is the same isnt hop utilization higher in the lower gravity beer?

 

If that's 6 gallons into the fermenter, and assuming some reasonable hop absorption and other losses before that, a 1.065 planned post-boil OG with that grain bill would need about 76% mash efficiency, which isn't super high, but might be a bit ambitious for a first batch.

- What was your actual volume into the fermenter?
- How did you crush your grains?
- What water and minerals (if any) did you use for the mash? This grain bill would produce a rather high-ish pH, even with distilled water. With alkaline water, it would produce an even higher pH, outside recommended ranges, which can affect mash efficiency.
- What was the temperature of the wort when you measured the gravity?
- You measured the gravity post-boil. Right?

Otherwise, your post boil gravity of 1.040 would imply a mash efficiency of about 47%, which is very low, and would indicate one or more problems.

 

Well, I actually assumed the discrepancy was due to him adding water at the end of his boil.

Now, if it was 1.040 without adding water then he will have more bitterness...but less hop flavor/aroma. If that makes sense.

 

So what was your actual post-boil volume?

Spring water could be anything. But I suspect your mash pH was pretty high, reducing efficiency. And... how did you crush your grains? Have you checked your hydrometer with plain water to see if it measures 1.000 at its calibration temperature?

It could end up being quite drinkable. I wouldn't waste time worrying. But I would start thinking about dialing in my process.

 

How would gravity affect the late additions in that way? Not being snarky, honestly curious. I figured late hop contributions would not be affected as much.

 

A pretty common cause of low mash efficiency is a bad crush, i.e. grains not crushed finely enough. A pretty common cause of a bad crush is letting the LHBS crush your grains.

If your post boil volume was higher than expected, that would partially explain your low gravity.

Any of the common causes of lower than expected gravity could happen with any batch size. I don't know why you think that's an issue.

That sounds pretty normal. And counting bubbles leads to madness.

So, here's where I think you are in diagnosing your low gravity...
- Possible bad crush
- Possible (unknown) high wort volume
- Probable high Mash pH

And I'll add one more... your grain weight could have been low, unless you weighed it yourself to verify what the LHBS sold you.

 

One last thought... your recipe's mash temp was 154F. Did you measure the actual temp of your mash after thoroughly mashing in (mixing the grains and water)?

 

I couldn't tell you, the mechanism. However, if you were to brew a 1.040 beer, and a 1.060 beer and hopped them exactly the same...the higher OG would seem hoppier (flavor and aroma) than the 1.040.

Now this may be more perceptual, than technical, I don't know.