Minor brew day screw up, could use a quick assist...

3rd all grain/partial batch, trying to do a partial mash IIPA. Went for a low mash temp (149), hit it pretty right on, but lost more degrees than expected over the 90 minute mash. It finished between 142-146 depending on what part of the pot I measured, so I was already worried about low conversion (I don't have any iodine to test with).

But then I went and spilled probably about 1/2-3/4 gal of the mash water (sparge water wouldn't have been as bad). Great...

So I went and combined and I'm bringing it to a boil anyway. I've got some extra LDME on hand that I can throw in to bring up the gravity, but I'd like to calculate how much to add. My recipe already called for 3 lbs LDME and 1 lb dextrose to be added. Can someone help me calculate how much extra LDME I need to bring the boil up to around 1.075 - 1.080 at 6.5 gallons (OG after evaporation around 1.090 @ 5.25 gal)?

Measured gravity at 145*, 6.5gal (without the 3lbs LDME and 1 lb dextrose already planned) is 1.020, I have no idea how many points to add for the 145*, nor how much this will go up when I add the planned LDME and dextrose... help?

145 deg w/ 1.020 becomes 1.037 I can't remember the cups of DME to gravity... but is that gravity w/. the LDME already added? somewhere here, if you search, there's something I've read that X cups of DME = 1.020 additional gravity or the like... Try the wiki?

I'll peek too.

Sorry not finding it... I did a quick test and 5lbs of LDME moved up to 1.038 OG on my software... if you were expecting it to go up more, then... something in that range will work. Don't count this as a guarantee. I'd add the LDME after you get ready to go... then see where your gravity is... From How To Brew, here's a table for the gravity per temps:

http://www.howtobrew.com/appendices/appendixA.html

Thanks...

The 1.020@ 145* was without the LDME or dextrose. I did some estimations and I'm guessing 1lb LDME = about .008-.009 gravity points. So this is my guess:

1.037 + .018 from evaporation = 1.055 + 3 lbs LDME = 1.079 + 1 lb dextrose (no idea how much this is, but let's say .012) = 1.091, so it would seem I'm in the right range already?? Not sure how that's possible, maybe I spilled less wort than I thought or got higher efficiency than I thought?

I did decide to add 1.5 lbs. LDME just in case though. I guess we'll see what the OG is once it's done and cooled.

On edit: if I use you calculations of 1 lb LDME = .007 gravity points I get what sounds more accurate, SG of 1.081 (assuming dextrose = .01 instead of .012). So adding the 1.5 lbs of LDME should give me about 1.092 which what my recipe called for... let's hope it worked!

Let us know. cheers

OG was 1.082... which is close to "good enough." I've heard you can add dextrose partially through a big fermentation to encourage the yeast, so I'm going to look into that. But 1.082 is probably close enough. Thanks for the help!