Gravity adjustment oddity

[BikerMatt]

A.k.a. where did I c**k up?

So this weekend I did a double boil, one friday night, second saturday night. Both ended up in the same fermentor.

3kg pale
200g munich

60min mash @ 67c

Just poured the second batch into the fermentor after a night of immersion cooling and took a gravity reading. Just as expected my OG was very high just as it has been on every boil, with a whopping 1.079 @ 17L I calculated that to correct the gravity to my desired reading, 1.050, I'd need to dilute the wort 9,8L. That however cannot be done because the fermentor can only accept 8L of water before hitting the max 25L. For a safety measure I replaced the bubbler airlock with a blowoff tube because there weren't hardly any headspace left in the fermentor.

Now the oddity part. Since I diluted the wort less than my calculation one would think my OG would still be over 1.050 right? Then why did I get the reading of 1.040?! Time will tell how much ABV will I be getting but to me that sounded odd. I did shake the vessel around what I could before taking the reading and pitching a bag of S-05 but I suppose it'd still be possible that I hit a layer of thinner wort on the top? Can't take any water out so I guess all I can do is wait and hope.

 

[wilserbrewer]

Given your 3.2 kg grain bill, your gravity of 1.079 on 17 l seems unreasonably high to me, why I have no idea.

Your reading of 1.040 on 25 l seems more typical given the grain bill and volume ime.

Assuming your 1.040 reading is correct, you should have had a gravity of 1.059 on 17 l.

Any chance you mistakenly read 1.079 instead of 1.059?

I'll wait with you for those more knowledgeable to comment.

 

[BikerMatt]

Thought that too but It definitely was a smidge over the 80 line. First thing that caught my eye when taking the reading was whoa that floater thing is trying to jump out of the tube! All by brews that I've done so far had been really high in OG, the El Fuerte that is bottle conditioning as I write this was done with the exact same grain bill and it has a manly chest hair growing 8,4%!!! I suppose my self made sparging bucket is draining every last bit of sugar from the grains or something, but my efficiency has so far been consistently and considerably higher than expected.

Edit: do take into account that the OG on this one was achieved with TWO boils so effectively the grain bill for the 17L was in fact 6,4kg.

 

[chickypad]

I'd suspect the reading after adding water may not be accurate, maybe a mixing issue. Regarding your OG being "very high" every time, I think you need to examine how you are calculating recipes. If I understand correctly you used 6.4 kg malt for 17 L finished and expected 1.050, instead getting 1.079? If my quick calculations are right 1.050 would only be about 45% efficiency, while 1.079 would be about 70% - perfectly fine but really not that high. Are you using software or a calculator?

 

[BikerMatt]

Well I do use brewer's friend, my problem is my boiling pot is only 15L so my pre boil maxes at around 13L, I was being a bit vague in the sense that I was actually shooting for a full 23-25 liters so I was well prepared to do a gravity correction dilute. I'm going for the reading being wrong after adding water.

 

[chickypad]

Ah, gotcha. So if we go with your original reading sounds all good and right on target.

 

[BikerMatt]

Small update on this one. Just popped in the garage a minute ago and the bucket is bubbling like MAD! I`ve never seen such airlock activity before, sounds like a small tugboat that goes like blub-blub-blub-blub-blub-blub-blub-blub-blub.... Took a peek inside too, good krausen but doesn`t seem to be reaching for the lid. Smells even better than it did before. Gon be a loooooong month and some before getting this in my pint.