Low OG in last couple batches

I’ve been getting low OG readings on my last couple batches of all grain brews. Like 1.020 or so. One was a pilsner and one an Irish red. What could cause this? I’m using a mash infusion calculator for mash tun capacities.

would really need to know a bit more about the recipe, grain weight/water volumes and how you mash/sparge but crush is the most likely suspect for low mash efficiency.

I don’t have my notes right now. I’ll have to get that info tomorrow when I get home. But how would crush effect that? I used the mill at the shop I buy my recipes and I did not adjust anything. I think for my Czech pilsner the wieght/water volume was about 12 qts water at 169° for 9.75 lbs grain if I remember right. (Approx.)

When the crush is finer you expose more of the endosperm to the water in the mash so you higher efficiency. Have you had higher efficiency before this last couple batches? Were you getting grain crushed at the same place?

9.75 lbs of grist sounds like a reasonable grain bill for a 5 gal batch of pils

How are you sparging? Batch, Fly, and in what? Sometimes you can get “dough balls” from not stirring enough or channeling from sparging too fast where the sparge water runs through without contacting all of the grain.

1.020 is way low so something is off. Hope we can remedy this.

The grain did look finer. The pilsner was from my HB shop but the irish red was from NB. I am sparging via my 10 gal igloo mash tun. I think that would be batch sparging. i did not stir except for when adding my grain. I will admit I am fairly new to all grain. I’ve done about 12 or so brews but just started having this problem.For the pilsner it rested for 1 1/2 hrs and the red for an hour.

Yes, double check yer mash temp, if it was as you showed 169, way too high, try 152, and an hour is fine. Sneezles61

If your strike water was 169 for about 10 lbs of grain you would have probably ended up mashing around 158 or so depending on your tun and the temp of your grain. That is a little high and would have probably produced a less fermentable wort but you still should have gotten a higher OG. @sneezles61 is right though that temp or a few degrees higher and you could potentially have been at a mashout temp that would have put the brakes on conversion.

Water was 169 b4 adding to grain. Brought mash to 152 ish. I did 90 min cuz I read about doing that with pilsner. This is the 2nd time I made the pilsner. 1st time I didn’t have this issue. Trying to take advantage of my basement temperature b4 it warms up.