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**Bobby_M** · 06-12-2009, 07:20 PM

I also thought since the chart doesn't cover all sizes:

Each quart of mash tun capacity can handle:
Max grain @ 1.25qt/lb = .6lbs
Total strike .1875 gallons
Total in tun .2435 gallons

**Laughing_Gnome_Invisible** · 06-12-2009, 07:23 PM

Quote:

Originally Posted by Boerderij_Kabouter

sticky vote!!!!!!!!!!!!!!!!

+1

23456789

**TheMan** · 06-12-2009, 07:41 PM

Wow, thank you Bobby! That second explanation you gave helped a ton. So basically I calculated the Max OG, not tun size needed. I think I have just one other question...the 17 you divide by, is that from the max OG calculation? Whereas, a 52 qt at 70% efficiency in 15 gallons would be (767/15 = 51) Meaning max OG of 1.51. I would divide by 15 instead of 17 in this equation: (Desired OG x Batch Size)/17 = mash tun size?

Or is the 17 a static number and I'm just over thinking this?

Quote:

Sorry, to clarify, a 52qt, assuming 80% eff. is good for 1054 total gravity points. In 15 gallons, that's about 1.70 max OG. (1054/15 = 70).

If you know your expected efficiency, you can try this. To calculate for mash tun size requirement in quarts (80% efficiency of course), it's (Desired OG x Batch Size)/17 = mash tun size

Thank you for your patience with me, I'm trying to understand.

**wilserbrewer** · 06-12-2009, 08:06 PM

Nice job Professor Bobby!

**Bobby_M** · 06-13-2009, 02:25 AM

The 17 is max gravity points per quart of mash tun at 80% efficiency. Another way to say it is that it would be 21 gravity points per quart at 100% efficiency.

You can rewrite the formula like (desired OG x Batch Size in gallons) / (21 x estimated efficiency in decimal) = mash tun size in quarts.

I think it's safe to assume a 70% efficiency though so just use 15 gravity points per quart of mash tun as an estimate.

**TheMan** · 06-13-2009, 03:20 AM

I've read and been messing with the numbers now for a little bobby, I get it now. Great write up, hopefully they sticky this, I'm sure it will help many people. Looks like an 80 qt. will be optimal for my needs.

Thanks again for helping someone as mathematically challenged as myself!

ohiobrewtus · 06-13-2009, 04:53 AM

Has this not been stickied yet?

wtf?

BeerCanuck · 06-13-2009, 01:20 PM

Nice post Bobby

Cheers
Steve

fidjit · 06-13-2009, 11:10 PM

Quote:

Originally Posted by Laughing_Gnome_Invisible

+1

23456789

Sticky Vote!

**jldc** · 06-13-2009, 11:17 PM

Thanks for the post.

My comments:

If you mash looser than 1.5 qt/lb, you will need a bigger tun.

A 5 gallon tun isn't a total waste. I use mine for smaller beers and as a HLT. Also, if you decide to move from a 5 gallon to a 10 gallon cooler, you may be able to replace the plastic valve mechanism or plug the hole and turn the cooler back into a cooler again.

All of that said, a 10 gallon cooler is only about $20 more than a 5 gallon cooler (if you're buying and not scavenging), and is money well-spent.