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Double batch questions

I’m planning on brewing a double batch of a beer that I’ve made several times before. It’s an Orange Cascade Pale Ale. I found the recipe on HBT about a year ago and have tweaked it several times over the last year and got it right where I like it. Now I’m planning on brewing a double batch and want to make a few adjustments, but not sure if I’m doing it right. Your experienced input is greatly appreciated.

First: I was going to have a 60min addition of 2oz of cascade hops for bittering. I’m thinking of subbing 1oz of magnum to give me just about the same IBU’s. My question is will there be a big noticeable difference in the final product? Magnum is clean bittering and I assume a 60min addition of cascade wouldn’t impart much or any flavor or aroma, so I’m wondering if this idea to sub 1oz of magnum in place of 2oz of cascade will work for what I want to do.

Second: Due to limited pot size and mashing amounts, I’d doing a partial boil and diluting with fresh water afterwards. According to the brewing program I use, I took my original 5 gal recipe, doubled the final wort volume to 10gal, kept the original average boil amount the same at 5.5gal and pretty much doubled all the grains and hops additions to get me back to the estimated OG,FG,SRM,IBU. So basically I’m brewing a very strong 5gal batch, splitting into two 2.5gal batches and then topping both off up to 5 gallons. Does all that sound right?

It does, but I’ve heard in very high OG concentrations, you get less utiization rates- so you may need to up the magnum even more than you have. I’m not sure where you would find a calculation to tell you, though. I think Palmer mentioned it in How to Brew. You could google his website to find more details.

Don’t forget when you add “fresh” water, you are introducing bacteria (a small amount) in the water- when you mix the water together, you want to hope that the resulting mixture will be above pasturization temps at 160 for at least 10 min. From what I calculate: 200*.5 , 145*.5 = 172.5 (145 seems to be my hot water temp out of the faucet).

Cascade has a higher cohumumone level (35 - 40%) than magnum (25 - 30%) and therefore will have a “harsher” bitterness. Think hop bite. Magnum is smoother. It won’t change the recipe THAT much, but it will be a little different.

+1 My American Stout is all Cascade but I didn’t have enough for all additions and subbed Columbus for the bittering and although Columbus is known as an aggressive hop, the bittering is noticeably subdued (and not in a good way, although I like the new pine component, so it’ll probably end up a wash).

Hopville tells me that 1oz of magnum (11.4 AA) will get me to about the same IBU’s as 2oz of Cascade (5.5 AA) for a 60min addition. So you’re saying I should up that a little more? Like maybe 1.25oz of magnum?

In addition to poor hop utilization, I would guess your efficiency would go down as well.

Doubling your malt bill would work if you were doubling the batch but what you’re effectively doing is making a similar sized batch at double the strength and then diluting which is different. My guess is your efficiency will suffer and so your OG will be lower compared to a single batch, unless the OG is really low like 1.035 or lower.

[quote=“cramer”]In addition to poor hop utilization, I would guess your efficiency would go down as well.

Doubling your malt bill would work if you were doubling the batch but what you’re effectively doing is making a similar sized batch at double the strength and then diluting which is different. My guess is your efficiency will suffer and so your OG will be lower compared to a single batch, unless the OG is really low like 1.035 or lower.[/quote]

Estimated OG is 1.056… but, I don’t have the ability to just double the grains. I should have been more clear about this earlier. My bad. This beer is gonna be a partial mash. So I’m doubling the crystal malts in the recipe, but leaving the base malt the same as a 5 gallon batch and adding extract later in the boil to try and get better hop utilization.

5 gallon full boil recipe:
10lbs 8oz - 2Row
12oz Victory
8oz C120
8oz Carapils

1oz Cascade at 60, 15, 10, 5, 1min
2oz Cascade dryhop for 14days.

10 gallon partial mash recipe:
10lbs 8oz - 2Row
1lb 8oz Victory
1lb C120
1lb Carapils
5lbs Extra light DME (late addition)

6 gallons boiled down to 5 then split into 2 fermentors and topped off to 5 gallons each.

1oz Magnum 60min
2oz Cascade at 15, 10, 5, 1
Dryhop 2oz Cascade in each 5 gallon batch.

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