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Grain absortion

So I did my first AG in like a year. I have Denny’s MLT made from a cooler. I had a 10lb grain bill. I did my strike calculation assuming the grains would soak up approximately 1 gallon of water. I mashed in with 4gals and was planning on a 3gal sparge winding up with 6gal in the kettle pre boil. I wound up about 2 gallons short. What happened? how do I fix it?

You should have lost about five quarts to the grain, so if you mashed with four gallons and sparged with three, you would have 5.75 gallons in the kettle. To only get four, you must be leaving a lot of wort in the mashtun. What are you mashing in, with what manifold, and do you have it set up to siphon from the bottom of the MT?

Grain usually absorbs about 0.12 gal/lb = 1/2 qt/lb. You may also have some deadspace in your mashtun that doesn’t drain.

Do you batch sparge? If so, just subtract your first runnings volume from your desired pre-boil volume and the result will be your batch sparge volume. There won’t be any more loss to grain absorption or mashtun deadspace. Easy-squeezy.

Cheers :cheers:

I am using an igloo cooler 48qt I think. It’s Denny Conn’s design ( dennybrew.com ). I have a steel mesh line at the bottom of the MLT where the drain spigot used to be. When my MLT is done draining, I’ll tilt the MLT toward the drain end. When I do, there is a lot of wort that collects but does not drain. I know my grains are holding more wort than they should. I considered pressing the grains but I am afraid debris will end up in my kettle causing tannin extraction.

And yes I batch sparge. I wondered if that was ok. Would it be better to add more to my strike volume or the sparge volume?

It’s not the grain that’s holding the wort, it’s the cooler. You could solve this by using a pickup tube running from the valve to the bottom of the cooler with the braid attached to the end - with the hose on the valve outlet you now have a siphon and it will suck up all but the dregs of wort.

If you don’t want to mess with your setup, you could bump your recipes up to compensate for the loss - reformulate to account for the ~2 gallons left in the MT.

I typically use 0.125gal/lb as the amount the grain holds. As for dead space at the bottom, I tip my cooler up and get it to drain as much as possible. I mostly do this on the sparge since at that point anything left is wasted.

+1 pick up tube does a great job.

I had a similar issue on my batch sparging system and solved it by jerry rigging two 90 degree elbows to get my braid flat on the bottom of my square cooler.

To do this, I fitted a male threaded to slip (ie glue) adapter to my ball valve on the inside of the cooler. This allowed me to fit a slip/slip 90 degree elbow to the adapter and a further 90 degree elbow to the first elbow. The braid is mounted on a 2 inch double insert fitting (barbed on both ends) and the insert fitting sits tightly in the second 90 degree elbow. Once everything is assembled, you simply rotate the first elbow until the second elbow sits flush on the floor of the cooler.

I initially intended to glue the fittings after doing an experimental run, but discovered that the slip fits are tight enough to withstand any banging around they suffer due to stirring, so I’ve left well enough alone and I’ve yet to have anything shake loose during a mash. As a precaution, I’ve replaced the two elbows from time to time, but they yield years of service between changes. I figure a buck in parts is worth the piece of mind.

Since adopting this system I’ve drastically reduced the amount of dead space in my cooler and I’ve observed about half a pint of liquid remaining in the mash tun during clean up. Combined with tilting the cooler, this system works quite well.

There you have it, a pick up tube for less than $3 in parts.

I brewed again last night and you guys are right. It is my MLT leaving the wort behind. Hey Troglodyte, if it’s not too much trouble, could you post a pic of your modification? Thanks for the help everyone.

Is your SS mesh collapsing? Can you tell? Are you sure it’s really stainless steel and not a painted plastic weave? You could try weighing it down and/or strengthening it with some copper inside. Or get a bigger, thicker SS mesh like the ones they sell for hot water tank connections – that is what fixed things for me.

Let’s see who’s smarter, me or the forum…

Ah ha! I win. Since this photo was taken, I shortened the pvc barb on which the mesh is mounted. This further reduced the amount of dead space in the tun. I’m sorry about the lousy image quality, but I hope it is sufficient to get the idea across.

Perfect. Thanks.

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