Musings on improving my RIMS bottom-drain mash tun setup

[blizz81]

I have an upside-down bottom-draining keggle in use as a RIMS mash tun using BrewHardware's tri-clamp kit + RIMS tube. Have a Jaybird false bottom + ring stand, but I had flow issues so we've been using a BIAB bag for lautering and the false bottom as more of a grant for the pump.

We were hitting around 77-78% brewhouse efficiency for a while on this setup. Wore a hole in the bag after years of use, so I bought another one and had some issues with a few bags being more tapered at the bottom and having a lot of wort outside of the bag. I cut the lip down pretty much to the keg wall and ordered a fabbed SS mesh basket. However, had similar issues as the rolled lip of the keg is really the limiting factor of me getting a mesh basket that will fit closely to the keg wall. Went back to the bag, and clipping it on what remains of the lip that I had cut down, giving the bottom of the bag more room, and it seems more like normal, but still 1) getting brewhouse efficiency around 70% nowadays with nothing else really changing in equipment or process, 2) still get a surprising amount of grain particulate matter in my wort, not sure how, don't notice any holes in the bag, and 3) if I attempt to stir the grain bed during the mash (while recirculating) in an attempt to work dough balls further, I run into problems with a suction effect of the bag against the false bottom and have to pull it up a few times.

Pondering upgrades with those things in mind. I want to stick to bottom-drain. It seems pretty much nobody sells bottom-drain kettles, though I could probably have someone like Spike do a custom build as I see they're doing bottom-drain on their Nano 3-tier. I haven't asked if they would be able to add a SS mesh basket tailored to the dimensions of their kettle as an option. If I want to go basket, I could also attempt to cut and re-roll the top (actual bottom) of my keggle, but my fear is that I would get another basket fabbed and the dimensions would still be off (the one I did order was smaller than specified by a quarter inch, and I'm more or less out that $ now unless I can find someone to buy the basket).

One option is improving the filtration on my keggle such that I wouldn't need a bag or basket. But I do like the ease of cleaning this provides, as I can pull the grain and clean the bag/basket separately, and then essentially CIP the keggle by recircing PBW vs. lugging a kettle around being careful with bottom-draining hardware (generally cleaning outdoors, which sucks in the winter in Nebraska).

I don't know if issue #3 is inherently preventable in a recirculating setup, or if it's a bag-specific thing. Is disturbing the grain bed in a recirc pretty much always a no-no? (Or maybe at best, turn off the pump / recirc, stir, let the bed set a bit again, and then throttle up flow again?). Having something motorized that continuously stirs the bed would be a nice pipe dream. With a mesh basket, I think a more realistic option would be drill + paint stirrer attachment maybe once or twice after the initial dough-in. I feel like either dough balls or my crush would be the remaining culprit on efficiency issues even if process hasn't really changed there - I measure crush, etc. Attempting to measure mash efficiency might be more accurate, but again, this all changed around the initial bag switch. Outside chance the knurling is wearing down on my BC rollers at the same time, I guess - crush seems to generally look ok.

Took a quick look at all-in-one units, but it seems they're largely no-sparge and end up around my 70% brewhouse efficiency anyways, and then I'd have to look at 240V, etc.

If you made it this far, thanks for putting up with my stream-of-consciousness babbling post!

 

[RPh_Guy]

Do you have a grain mill? Try conditioning your grain. Lautering and flow will improve immensely.

 

[blizz81]

Do you have a grain mill? Try conditioning your grain. Lautering and flow will improve immensely.

Agree! Yeah, we condition our grain - it definitely helps fluff up the grain bed.

 

[augiedoggy]

the other option is to improve your false bottom or slow the flow down thru the grainbed. I also recirculate and use a rims, I cruch with a gap set by using a credit card and I do not use rice hulls. I get a very consistent 91% average brewhouse efficiency I think this is because of two things I do differently,
I recirculate at a low flow rate of between 1.5-2 gpm when mashing and sparge about 1gpm.
I have a bayou classic kettle and false bottom but I have a long section of coiled up stainless braid attacted to my dip/drain tub to act as a fine second filter. this is beacuse I use small dc pumps but found it aided in my efficiency.

with slower flow you will eliminate channeling and your efficiency will jump.

 

[blizz81]

the other option is to improve your false bottom or slow the flow down thru the grainbed. I also recirculate and use a rims, I cruch with a gap set by using a credit card and I do not use rice hulls. I get a very consistent 91% average brewhouse efficiency I think this is because of two things I do differently,
I recirculate at a low flow rate of between 1.5-2 gpm when mashing and sparge about 1gpm.
I have a bayou classic kettle and false bottom but I have a long section of coiled up stainless braid attacted to my dip/drain tub to act as a fine second filter. this is beacuse I use small dc pumps but found it aided in my efficiency.

with slower flow you will eliminate channeling and your efficiency will jump.

I’ll give a slower flow rate a shot next brew. I don’t notice a ton of channeling visually but I do tend to crank it open after the grain bed settles.

 

[blizz81]

Well, I didn’t get to mess with flow rate on my brew this past weekend as my latest idea backfired. I decided to put a smaller bag under my false bottom ring to catch the particulate matter that had somehow been coming thru my bag and false bottom. That totally killed flow, couldn’t recirc.

Decided to cut the top (or technically, bottom) ring of the keggle off at the weld line yesterday. Going to give another SS mesh basket a shot, and probably try a new 2-roller mill as my BC is somewhere around 9 years old.

 

[augiedoggy]

yeah if the second filter under the false bottom doesnt provide enough surface area, its likely to plug right up I ran into this myself and this is why I have 30" of braided stainless coiled up under my false bottom.

 

[JaymzMF]

The biggest change for me in efficiency was stirring the mash. I never had and I had efficiencies all over the place. I use a HERMS so I always thought I was good since I am maintaining a perfect mash temp but there are hot/cold spots throughout the tun. I stir every 15 minutes to keep nice even temps. I'll turn off the flow. Stir well. Slowly start up my flow again. Some may think this is excessive, but I am getting 90% efficiency now.
Something that helps with the false bottom since I do get a stuck mash occasionally, use silicon hose around the outer edge of the false bottom. That helped a lot too.
Also, recently started building my water profile off of RO or distilled water and watching my ph. This has helped me too.

 

[Vale71]

There can be no significant temperature differences provided you have a uniform flow through the grain bed. This can only be the case if you have significant channelling which stirring frequently would help disrupt and this is probably what you are experiencing.

 

[blizz81]

The biggest change for me in efficiency was stirring the mash. I never had and I had efficiencies all over the place. I use a HERMS so I always thought I was good since I am maintaining a perfect mash temp but there are hot/cold spots throughout the tun. I stir every 15 minutes to keep nice even temps. I'll turn off the flow. Stir well. Slowly start up my flow again. Some may think this is excessive, but I am getting 90% efficiency now.
Something that helps with the false bottom since I do get a stuck mash occasionally, use silicon hose around the outer edge of the false bottom. That helped a lot too.
Also, recently started building my water profile off of RO or distilled water and watching my ph. This has helped me too.

I'm planning on slowing my flow a bit and probably stopping halfway and killing flow, stirring, letting it set again, and ramping flow back up. I've measured temp with a long probe before throughout the mash and it's generally been pretty uniform, and I would think even some small fluctuation in temp shouldn't really cause much of an issue with sugar extraction, but I've been concerned about dough balls more. I did notice that last brew day when I had my wife help dough in vs. my usual more hasty brewer's assistant, I had a much easier time simply due to us adding grains more slowly.

Unfortunately I may not get a great answer as I plan on changing a handful of variables at once, but I'll report on my success or failure once my now-actually-keggle-sized SS mash basket gets to me and I get a brew in with it. When I did use my original SS basket for one brew day, I didn't have any issues with particulate matter getting through, so I imagine that will be fine now / my false bottom is more just acting like a stand for the basket. Ordered a MMPro2 as well.

 

[augiedoggy]

^ what Vale71 said... I believe the majority of home brewers who recirculate are shorting them selves of efficiency due to recirculating too fast and channeling. a lot of this is attributed to the 7gpm pumps most use and the design of many of your run of the mill rims setups not working well with low flow due to scorching and carmelization. the fancy tech is doing more harm than helping for many and its one reason many quite using such systems and go back to basic coolers or biab.

Generally the "baskets" are inferior as they let much of the flow completely or partially esape the grainbed and flow around the grain instead of through it.
think about something... you want EVEN consistent flow through the whole grainbed like liquid through a filter bed... now if you put the filter media inside a basket or preforated tube with space all around it, whats to stop much of that liquid from taking the path of least resistance around it? for recirculating mash system they are more of a gimmick.

 

[JaymzMF]

Something else I was just reading in another thread of a guy that puts a stainless steel mesh under the false bottom at the pick. This may help your flow since you had mentioned stuck mashes when stirring. I don't remember who stated this so sorry for no credit given to them. I plan to try this myself because I do get stuck mashes from stirring.

 

[blizz81]

^ what Vale71 said... I believe the majority of home brewers who recirculate are shorting them selves of efficiency due to recirculating too fast and channeling. a lot of this is attributed to the 7gpm pumps most use and the design of many of your run of the mill rims setups not working well with low flow due to scorching and carmelization. the fancy tech is doing more harm than helping for many and its one reason many quite using such systems and go back to basic coolers or biab.

Generally the "baskets" are inferior as they let much of the flow completely or partially esape the grainbed and flow around the grain instead of through it.
think about something... you want EVEN consistent flow through the whole grainbed like liquid through a filter bed... now if you put the filter media inside a basket or preforated tube with space all around it, whats to stop much of that liquid from taking the path of least resistance around it? for recirculating mash system they are more of a gimmick.

That seems to make sense. Do you think there's much of a difference in the baskets vs. a BIAB bag? In theory a bag will completely hug the lining of the vessel, but in my practice it seems this has never quite been the case, be it by means of air bubbles and/or wrinkles. It could be a result of having too large of a bag for the vessel I suppose. I did used to hit around that 77-78% brewhouse efficiency mark for a while with a keggle bag though.

I'm aiming for as minimal area between the basket and the keg wall as possible on basket #2, but obviously that can only be optimized to a point. I would think I could probably poke some holes in my silicon return tube and stick it vertically down the center of the mash or something similar. Seems like it's going awfully far to just make cleanup a little easier vs. surrounding the false bottom and stand in mesh alone and having to clean grain out the keg, but then again I do like to use this hobby as an avenue for overcomplication.

 

[blizz81]

Just to update in case anyone comes across this thread. First brew day since getting a MM2 Pro and a new mash basket since cropping the top of the keggle. Set mill gap at .035, still seemed like I can go a bit more aggressive there (the 1.25lb of 2-row I put thru dry to clean the rollers was crushed well, but we condition our grain and there were a lot of cracked but mostly visually intact husks). Visually it looked similar to recent crushes with the BC.

Stirred three times during the mash. The grain bed responded well to that with the mash basket, where stirring with a bag has led to some suction / flow issues. Doughing in, the mash was a bit thicker than normal - there’s a smidge more volume below the grain bed than before, and the basket fits tight but still a bit of volume outside. I figured this would be balanced by the extra bit of volume I’d get using a press plate vs. letting the mash sit for a bit and adding drainings early on in the boil.

Was recirculating probably not as fast as I had been, but also not entirely slowly. I had planned on putting holes in the bottom of my silicon return tube as opposed to curling it on top of the grain bed, but that proved to be not trivial after testing drilling thru silicon so I went back to the curl.

I have notches in my BK stir paddle for volume so somewhat of an estimate for volume into FV, but had a calculated 78.8% brewhouse efficiency. Seemingly back in business. Changed enough things at once that I can’t say exactly what helped.

I might explore a stainless tube with holes down the middle of the mash with diameter such that I can fit my silicon on over it, as that would make my fashioned lid more effective.