mwright Senior Member Joined: 6 Sep 2010 Posts: 102 Location: Michigan Expertise: I like coffee
Posted Mon Aug 27, 2012, 4:54pm Subject: Bonavita Brew Basket Bed
This is what my coffee bed looks like after brewing. The pick is not the best but it shows a large center hole with the the coffee pushed up the sides. I am using a Baratza Virtuoso on setting 24 but I have tried some other settings as well. Does this seem normal? I saw some pics on line of the grounds bed and they seem pretty much flat after brewing. Any ideas? The filters are white Melitta.
EvanOz85 Senior Member Joined: 9 Jul 2011 Posts: 258 Location: Lafayette, LA Expertise: I live coffee
Espresso: La Spaziale Mini Vivaldi II Grinder: Baratza Preciso, Hario... Vac Pot: Bodum Santos, Yama 5-cup Drip: Chemex, Kone 3, Kalita Wave,... Roaster: Behmor 1600
Posted Mon Aug 27, 2012, 5:06pm Subject: Re: Bonavita Brew Basket Bed
Never used the Bonavita, but a convex bed is typical of any pouring style that focuses on the center of a cone. Give it a stir once all the water has been deposited and that should give you a flat bed.
Posted Wed Aug 29, 2012, 4:12am Subject: Re: Bonavita Brew Basket Bed
(Bonavita is an auto-drip, right?)
There's one of two things that could be going on:
Delivery rate > percolation rate. In this case, the basket fills with water but the distribution head is delivering water in the center. As the bloom tops over the solution can't percolate through the center, so heads to the side of the filter basket. At the end, the grounds have "crawled" up the sides of the basket, left deposited high and dry and probably underextracted.
OR:
Delivery rate < percolation rate. In this case, the coffee hits the center, the bloom pushes the coffee out and then the solution drains right through the center.
I'd bet it's the former (rD > rP), so try grinding coarser and see how that works.
I've found (YMMV, of course) that the Melitta filters are prone to clogging with fines, which may slow the perc rate.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
mwright Senior Member Joined: 6 Sep 2010 Posts: 102 Location: Michigan Expertise: I like coffee
Posted Wed Aug 29, 2012, 9:55am Subject: Re: Bonavita Brew Basket Bed
I have tried different grinds without a lot of luck. I do have some new filters coming today to try (Filtropa's). If I pull the carafe right after the water stops flowing from the spray head it alomost looks level but what actually is happening is that their is a lot of water in the center that has not drained out yet. As that water slowly drains it leaves the middle like it looks in the pic sometimes worse. The strange thing is every once in awhile it will be a more flat bed. I usually try to use a setting between 22 to 24 on my grinder but I have gone coarser with the same result. I am not sure what setting other typically use. Thanks for all the help.
Posted Wed Aug 29, 2012, 10:21am Subject: Re: Bonavita Brew Basket Bed
I am guessing this is a bloom issue. One clue is the "foam" on top of the grounds in your picture, that doesn't usually happen with older coffee. Very fresh beans (within 4 days or so of roasting, less so after that, although it depends on the bean and roast levels) will foam up the moment hot water hits them. This causes them to float. You can get underextraction this way if you don't stir the grounds up and break up the foam. This could also explain why sometimes it looks better than others: the older beans foam up less.
Try this: after some water has filled the basket, stop the brew and stir the basket grounds to break up the foam. You might have to do this more than once. Once the foam has dissipated, let the brew continue normally. Unfortunately, not all brewers make this "stop and stir" process convenient, and I am unfamiliar with the Bonavita to have a feel for how convenient this is for you.
This may also be partly caused by the drip pattern in the brewer, as others have said. Stirring part way will help this as well.
Posted Wed Aug 29, 2012, 2:02pm Subject: Re: Bonavita Brew Basket Bed
It's a pain, but you can also attempt some bloom suppression with cool or warm pre-infusion. Works for me to suppress bloom in the AeroPress, where every ml is precious. I've also done this with my BCM-4C.
Add the weight of your coffee in water to the grounds, and stir them up really well. The grounds will be fairly dry, and you'll make a thick paste about the same consistency of spent grounds.
This can be room temperature water, or mildly warm. I'd avoid hot because that will start solvation, but i'm sure that would probably be fine also. I think it works fine in the basket.
Then, level the grounds out and start your brew cycle. Try this with your current grind, several steps finer and several steps coarser.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Well I have tried some different things. Tried different filters - no difference Tried the room temp pre infusion - no difference The machine does not lend itself to turning on and off to try pre infusion. Calibrated the grinder coarser and tried a setting of 28. At the end of the water delivery the brew basket was 3/4 full of water and it took over 1 minute to drain fully. Tried a setting of 20. Basket almost completly full of water and took well over a minute to drain including what seemed like almost stalling at one point.
If I let it drain without me interfering such as swirling the brew basket I get that big v shape. The really long drain down times are concerning as well. I am wondering if I am geting a lot of fines. I also noticed this same slow drain when I used my Tiamo dripper (Kalita clone). This slow drain has gotten worse lately.
OK I tried it on setting 35 on my Virtuoso and still the same thing. 3/4 of the way full of water and taking well over a minute to drain. Any ideas. The coffee is obviously pretty coarse at this point.
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