Author: Marshall Schott
Rex from The Brew Bag is, perhaps obviously, a huge proponent of Brew In A Bag (BIAB), the relatively modern approach to mashing that originated in Australia, and is adamant about destigmatizing the approach. I typically mash in converted cooler MLTs because I often make batches too large to fit the full volume in my kettle, though I absolutely see the value in BIAB and find myself utilizing the method on smaller batches with absolutely no ill-effects. Over the last year or so, Rex and I have engaged in a few conversations about the merits of BIAB and in a recent chat he asked if I’d ever considered using a mesh bag filter in my MLT in place of my current stainless braided hose. I hadn’t, but it seemed like a viable and uncomplicated option. He offered to send me a bag custom made to fit my cooler in exchange for an honest review. I received it a week later and put it to use the following weekend.
Just like my BIAB kettle filter from The Brew Bag, this was of extremely high quality with strong seams and tightly attached handles. I was sort of expecting the bag to fit my cooler a bit tighter, but I actually appreciated the extra material because it decreased the likelihood of the bag slipping off the edges into the tun. Prior to mashing in, I removed the stainless braid from the inside of my MLT and left the ball valve in place, though draining could easily be done using the proper diameter hose with an inexpensive inline ball valve. I followed my typical brewing process for this 10 gallon batch of Vienna Lager, which began with overheating my strike water by 7°F, filling the cooler to pre-heat, then mashing in. After 45 minutes, I collected the first runnings and added it to the kettle.
So far, so good. The biggest difference I noticed at this point was that the wort was crystal clear immediately upon opening the valve, not a single fleck of grain. While I remain doubtful a vorlauf is all that necessary on the homebrew scale, there was something satisfying about seeing such clarity so quickly. I added the sparge water, stirred, then immediately collected the second runnings without waiting for the grain bed to settle like I usually do– again, crystal clear wort right out of the gates.
This is where I noticed another difference. I have my BeerSmith equipment and mash profiles setup precisely for my typical batch sparge process. Going into this review, I figured everything would be about the same since I was only changing the filtration device. Surprisingly, the sweet wort continued to flow after I’d collected my target pre-boil volume, so I had to cut it off early. Moreover, a refractometer check revealed I’d overshot my gravity by .002 points… better efficiency from using a bag? I’ll take it.
Once I got the flame going, it was time to clean-up.
The mere act of picking up the bag caused even more sweet wort to be squeezed out, I’m guessing at least 2 liters, probably more. Next time, I plan to use my BIAB mash profile to account for less grain absorption, it felt weird pouring that extra wort down the drain. I proceeded to dump the spent grain, give it and the cooler a quick rinse, then lay it out to dry. The entire process took less than 4 minutes.
Similar to the pre-boil SG, the OG of the boiled wort was over target, leaving me with a final brewhouse efficiency of 82%. I’m not complaining.
| THE VERDICT |
Let me get this out of the way, again: BIAB is all-grain! I’m not bothered by much, but pretentious remarks about BIAB being anything other than all-grain can get annoying. Now that that’s taken care of…
I’m already a fan of The Brew Bag, but I rarely use my kettle filter because I often brew larger batch sizes. The Brew Bag’s mash tun filter fixes this problem, I really like it and think it’d work beautifully for prospective brewers who want to jump right into inexpensive all-grain brewing as well as experienced brewers looking to either bump their production volume or simplify their process. While I only reviewed the bag that fits my rectangular cooler, there are options for the popular round coolers as well.
Concerned about lifting a heavy bag of spent grain? Worry not! The Brew Bag sells really awesome pulleys to make lifting super convenient and easy on the body.
Rex is passionate about homebrewing, particularly when it comes to spreading the word about BIAB, and he contributes lots of valuable information to the community. If you’ve been considering BIAB, I have absolutely no qualms recommending The Brew Bag’s awesome products, have a look for yourself!
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70 thoughts on “Product Review | The Brew Bag Mash Tun Fabric Filter”
This is what I’ve been doing for years. It’s fantastic. I tightening my grain mill and I get 90% efficiency with no tannins. Super easy cleanup, super cheap.
I just took a look at their site and they don’t mention a warranty or guarantee. Did the one you receive come with anything to that effect? I may want to pick up a bag but I’m worried about longevity.
Adam – if the bag ever comes unstitched or fails from a manufacturing error, we’ll replace it. If you rip it, we’ll send you a patch. The bags are good for over fifty uses – we don’t know of a case of one wearing out or failing.
Sounds awesome. Thanks for the reply!
This is what I’ve been doing for a few years. I tightened my grain mill gap and routinely get 90% efficiency on beers 1.065 and under. Its so easy, cheap, and effective. It’s a great way to go. It’s especially easy to do when making the jump to all-grain from extract brewing.
I think that the basis of BIAB stigma is the name – Brew in a Bag. It sounds so amateurish. Time for a new name! Who’s got one?
I just call it a fabric filter.
How about a new name for the process, though?
Don’t drain pour the extra sweet wort, put it in a ziplock, freeze it and use it instead of DME for a starter.
Duh! Great idea, Paul.
I’ll second that idea.
In fact, I was about to leave a comment to say it anyway.
You can freeze it or put it in mason jars and pasteurize them for future use.
I’d be compelled to dilute it to ~1.035-1.040 then give it a 2-5 minute boil before storing it, but yeah, this is a great idea.
I do the same, especially when you need a 3.7 liter starter, that would be a ton of DME.
Would you think this would work for RIMS with a cooler such as yours? instead of a copper manifold on the bottom.
Never used RIMS, but I think it’d work fine.
Provided the holes are on the bottom of the manifold it works the same.
Kind of a weird hybrid application, but I thought it might offer another level of filtration and easy clean up. Looks like I will have to try it!!
I have been using the brew in the bag with my rectangular cooler for years and I am always amazed to the clarity of the wort and the ease of clean up.
Did you modify your grain crush at all? Seems a lot of BIAB users crush finer
For this review, I did not, yet still achieved higher efficiency. Perhaps Rex will chime in, but I believe he sets his gap to .025″ (mine is at .030″) and gets closer to 90% efficiency without any clogs whatsoever. I’ll likely be doing this soon 🙂
My mill is pre-set at .045 – and eff is always between 75 and 85. Next mill will be adjustable, I got it before I knew this could be done. But, with a fabric filter you can crush to flour and never worry about a stuck sparge. Conversion is quicker – 30 to 45 minutes – and more complete because more of the endosperm is exposed. Also, Troester and Briggs both proved that a WTGR ratio of 2.6 created the best combination of conversion and efficiency, so if you’re using a cooler try increasing your ration and crushing finer, you’ll likely see a good increase in eff – which means you can cut your grain bill back next go around.
I have a braided hose cooler mash tun. To avoid the bag getting sucked into the hole, would leaving the braid in be advisable? I wondered if it would negatively effect the whole purpose of the bag? Thanks.
No negative effect at all!
Thanks. For curiousity’s sake, any hypothesis on why the bag produces clear wort and why an improvement in efficiency? Vs braided hose or copper manifold.
I think the bag is such a fine filter, not much is allowed through, hence the clarity.
I’ve found d that the bag will bunch up (suck in)at the drain hole and slow drainage to a trickle. Ive rigged a small perfected piece of metal over the top of the drain hole that keeps the bag back. Anybody else had this happen or devised any other solutions? Other than that I think bag in a cooler is brilliant…and yes I have tightened my gap and improved efficiency. I think I like the EZ clean up best though.
I cut a SS 90 degree elbow and it worked for a couple batches, then it started getting sucked in. Now I use a bazooka tube I had laying around and it works great. The fabric catches on the folded end a bit but no tears yet. You could try shoving long spoon down the side of the MT and over the hole before you drain.
The perforated baffle works fine and it was something I had laying around . Just wondered if anyone had anot her interesting fix
Yup – you can also just pull the top loops back away from the drain hole and close the lid on them. We have also started including extra strapping with every order so you can loop it through and tie it off.
This happened in my 10 gal round cooler. I “liberated” an unused Tupperware bowl that fit perfectly on the bottom of it and sloped up to create a dead space to hold the bag back and for wort to drain out (after I drilled a hundred little holes all around it- a home made collander). After the drain, I lift the bag out, let the remaining wort drip out, lift the bowl out, and pour out any remaining wort for a no MT loss.
Glad to see you finally made the switch 😛 Next time, mill tighter and do a full volume mash instead of sparging. It’ll save you time / a step, and get the same or higher efficiency.
For grain absorption, I go with 0.08 qt/lb, so the difference in grain absorption or a 10 gallon batch could easily be 2 qts. There was likely even more wort stuck in the grains after you pulled it if you didn’t squeeze or let it drain naturally.
Yes, no need to sparge. That is a major selling point of BIAB.
It also sounds like it’s time for a BIAB squeeze the bag vs. don’t squeeze the bag xBmt. You could compare efficiencies, as well as the taste of the final product. Or perhaps just a good old BIAB vs. traditional all grain xBmt.
The efficiency in BIAB is locked in to the same degree as conversion. Squeezing adds volume of the same gravity, but, you could have higher post-boil gravity and hit your target volume by boiling longer. Sugars remain while water evaporates.
The thing most 3V guys are not accustomed to is accounting for grain absorption and recapture fm squeezing, and that can be a substantial amount of water, particularly on big beers. You’ll get 6-8 oz back from squeezing or draining fro every pound, so on a 20 lb grain bill that’s nearly a gallon. I use 12 oz per lb as a post squeeze number. In addition there is no dead space because all the wort is available after removing the filter. As Marshall dumped wort – all I could think of – what was the real efficiency transfer without the excess water?
“While I remain doubtful a vorlauf is all that necessary on the homebrew scale”
well that sounds like an Xbmt
You know it’s on the list!
Bought a Brewbag for my 10 gallon mash tun after reading this because i was having issues with my false bottom. It worked great and I love it. Also very easy to clean. Great product!
I lost 8% effeciency with this… I dont know what I could’ve done wrong 🙁 I always hit my numbers but wanted to make my life easier and bought this brew bag…
Did you stir throughout the mash? Crush finer? Keeping everything equal, I’ve gained 2%, though I plan to start milling finer since I’m fully converting to this method.
Safe to assume it’s the stir. I usually stir very well at the start and the end. As I stirred I kept getting caught in the bag, and it twisted with the spoon, pulling the bag in and preventing me from stirring as it twisted with the mash paddle. I got annoyed and I probably didn’t stir as much as I did with my FB.
Will probably clip the bag or do an X with bungie cords going around the bottom from one handle to the other. I still don’t see how this will prevent the bag from getting caught up in the paddle though… only prevent it from slipping in.
When using a fabric filter there is no need to set the grain bed – so you can increase your wtgr to full volume with the exact or better results as sparging. In my experience with wtgr above 2 there is no need to stir after mashing in. Post mash in stirring does not promote higher conversion and if the wtgr is above 2 the wort passes through the grain easily. In effect, the sparge water is added all at once – Troester confirmed that a wtgr of 2.6 contributed the highest potential transfer of sugars to the boil kettle. I now set my eff calcs at 78%, grind finer, use less grain, and after a few more brews will likely raise my eff calcs to 82%.
So you don’t stir during mash? A lot of BIAB’ers I’ve read mentioned they stir every 15 minutes (although they may be using a kettle rather than a cooler and need to monitor temps more closely).
Do you typically perform 60 or 90 minute mashes? So many BIAB’ers have mentioned they always do 90 minute mashes.
Are you a bag squeezer at the end of mash or do you skip that and just factor that water loss into your starting volume?
I got a stuck sparge on my last batch, where every second was spent thinking “Why didn’t I buy this bag Marshall told us about, whyyy?”. Now it’s bought. Also: the price for delivery in Europe is amazingly low (12$, a fifth of the price).
I don’t think you’ll regret your decision a bit. I’ve converted both of my MLTs to this method, couldn’t be more pleased. Cheers!
I just purchased this bag today. After some how last week when brewing I got a bunch of grain getting into my copper manifold and causing a horrible clog in my ball valve. I have never done BIAB. I am a Beersmith 2 user. How would you recommend I setup my cooler and mash profiles. I was doing about 1.25qt/# before using the default crush on my Barley Crusher.
I no sparge my 5 gal batches and simply uncheck the option to adjust for MLT loss, it’s worked great. You can also tighten your mill gap.
So full volume water mash on 5 gallon batches?
That’s right.
John – when you do full volume and a fabric filter a couple of calcs change. Since you can squeeze the grain to deliver more wort, the grain absorption drops to about 12 oz per lb. Also, no dead space calc. So you need to calculate fermenter volume, grain absorption, evap loss, trub loss – and by the way, pellet hops absorb 7 oz per oz, so if you’re using a lot of hops assume that loss as well.
Thanks for the replies. I got the bag Monday and brewed a 5 gallon batch of pale ale Tuesday night. Tightened the mill gap a bit and did a no sparge full volume mash. Worked out great. Easy clean up, man I wish I had this bag from the beginning. Efficiency was over 80%.
I have the exact same cooler and was thinking of picking one of these up. Do you happen to remember the dimensions you have Rex?
Not currently on my computer, but perhaps Rex can look it up?
I guess I could stop being lazy and measure the damned thing myself… But where’s the fun in that? ????
Same boat. Measuring shit gets in the way!
How quickly are you draining the mashtun when it comes time to empty into your boil kettle?
A little confused by the question, but either way, I open my valve all the way and drain as fast as I can.
Thanks! That’s what I was wondering…was curious if you had to throttle back transeferring the wort from the mashtun like you do when just using braided hose without the bag. I’ve just acquired the same cooler and going to make the transition from BIAB to BIAC.
Love your website…hands down my favorite brewing site!
I haven’t had to throttle back. Cheers!
Hello, question. I just picked up one of these. On the brew bag site, it mentions:
You can also use the The Brew Bag® as a complete Brew In A Bag NO SPARGE mash tool. Just calculate the full pre-boil volume, add approximately 12 ounces more water per pound of grain (this will be absorbed and tossed). Then just open the spigot and drain into the boil kettle. You may need a bigger mash tun for this process.
Have you tried this method before? Wouldn’t you want at least 1 sparge?
That’s the typical batch sparge method! I’ve done it plenty of times, it works great.
What is the capacity/quart size of the cooler that you are using? I’d like to do double batches as well…
70 quart
I just wanted to pop in and give my $.02. I just got by Brew Bag last week for the same cooler as you. I went no sparge, mashing in with full volume. I had assumed by mash efficiency would be 72%ish since I’ve hovered around that in the past with no sparges. Imagine my surprise when I hit 85%!
I tightened up my mill a bit to test the bag and it passed with flying colors. Clear wort with no vorlauf and with the valve wide open. It just doesn’t get any better than that. This has made my brew day so much easier – I couldn’t recommend it any more highly.
My brewhouse efficiency tends to hover around 72% using this method. Good stuff!
Do you mash out? If so then how?
I don’t 🙂
Marshall, when explaining that you removed your stainless braid you mentioned that someone could get away with using an inline plastic ball valve with the proper diameter hose. Did you mean that you could leave the drain that came with the cooler in plae and just hook a hose up between that drain hole and the plastic valve?
Thanks so much for the website… new home brewer and I’ve learned a ton here.
By plastic, I meant nylon, sorry about that. I’ve heard of people using just the standard plug that comes with coolers, but I’ve not tried, so I can’t say with any confidence whether it works or not.
Thanks for the kind words. Cheers!
Curious, I just used mine for the first time, love how quick I can empty the mash tun, but definitely turbid. No large particles but most definitely not clear like a braid with vorlauf. When you say crystal clear do you mean clear or no husk material?
Can this bag be used to during the boil process to keep hops from being syphoned into my chiller?
Absolutely!