Brewzilla + Mash Thickness

[Pugh]

I'm keen to know if there are others with biab brew systems that struggle to stick to recommended mash thickness in recipes?

I tend to find that I need to have more water in to mash the grain in my grain bill. Has anyone experienced the same? Does it matter? I'm struggling to hit ideal OGs and wondered if it might be connect to that.

 

[London]

How you treat your mash water, depends on your starting pH and desired pH. 20ml of AMS without knowing your water profile is completely arbitrary.

Mash for an hour minimum, you'll get better efficiency.

Regarding your water volumes, I wouldn't go down the route you've suggested. Instead 18-20L strike water (mash) every time, it's personal preference really - I rock 19L. Sparge to 28L preboil taking into account grain absorption at ~1L/kg. Boil for an hour, then you'll have 23L into the fermenter or damn near it. Boil off rates vary marginally, but are usually around 4L/hr @ 1900W.

So to calculate your sparge amount, using 5kg pale malt in a 20L mash as an example.

20L - 5L = 15L (that's what's left when you remove the grains).
28L - 15L = 13L (this is your sparge amount to make 28L preboil).
28L - 4L = 24L (this is your post boil volume after loosing 4L to evaporation).

The last litre is lost to cooling shrinkage. It's not actually lost, but would appear that way if you were to go by graduation markings on the kettle. This is around 4% from boiling to yeast pitching temp.

24L x0.96 = 23.04L

That's the full breakdown, but basically all you have to remember is that: Sparge volume = 28 - (mash volume - grain weight).

This should help, it's what I use and works great.

 

[foxy]

I'm keen to know if there are others with biab brew systems that struggle to stick to recommended mash thickness in recipes?

I tend to find that I need to have more water in to mash the grain in my grain bill. Has anyone experienced the same? Does it matter? I'm struggling to hit ideal OGs and wondered if it might be connect to that.

If you are concerned about efficiency there are a few things come into play, mash pH, crush of the grain, sparge.
I think De Klerk states 2.5 to 3.2 litres / kilo of grain if you are wanting to know the ratio.
http://braukaiser.com/wiki/index.php/Understanding_Efficiency

 

[The Baron]

I always work with more water than recommended in my single brew system and I am not alone I tend to use 4.5 ltr per kilo approx

 

[Pugh]

This is great, thanks all. Along the right lines then!

 

[cheeseyfeet]

There's 5l recoverable mash dead space in the bottom of the robobrew under the mash pipe, so this can knacker a lot of calculations .

I use 19 or 20l strike water in mine with success.

Weirdly I only ever get about 2l of a boil off, which doesn't seem to fit others experience.

 

[fury_tea]

I sometimes struggle to have enough 'to-temp' sparge water due to only having a 10L stock pot to sparge from. Usually I start with 24L, add my grain, then sparge with whatever else I need to get me up to my preboil volume.

After a few jugs of sparging water over the kettle, I often take the malt pipe off, put it over a 12L FV that's exactly the right size for the malt pipe to fit over and sparge over that, so I can measure exactly how much sparge water I need to add.

The mash is a little loose sometimes, but I have never missed SG by more than 0.001 and usually go over by a couple of points.

Seems to work for me.

 

[DCBC]

I was never happy with my results when doing full-volume BIAB. My beer was often under-attenuated and I frequently had bottle bombs, something which simply doesn't happen now I have moved to 3:1 water to grain ratio batch-sparge infusion mashing.

When you think of enzymes and substrate, if you have too much volume of liquid the enzymes and starch molecules are much further apart. You can visualise it as foxes and chickens in a pen. If you put ten of each in a tiny pen, all the chickens will be dead in less than an hour. Put them on hundreds of acres of parkland and you can bet that most of them would have survived after the hour is up! The amount of collisions that enzymes can have with starch molecules in a given time decreases with a thinner mash. You're therefore less likely to have full conversion after an hour with a thin mash (and you don't get any thinner than full-vol BIAB). My over-carbed bottles I believe came from having too much residual sugar after fermentation stemming from an imperfect mash, that slowly fermented out in the bottles.

I think the way round this would be, as indicated above, longer mash times or stirring of the mash every 15 mins (something you should never do in infusion mashing as this would mess up your nice grain bed!). That said, I have moved away from BIAB now so never got the chance to try. If you can get it right, BIAB is a great way to brew for most people, for sure.

 

[The Baron]

There's 5l recoverable mash dead space in the bottom of the robobrew under the mash pipe, so this can knacker a lot of calculations .

I use 19 or 20l strike water in mine with success.

Weirdly I only ever get about 2l of a boil off, which doesn't seem to fit others experience.

thats exactly the amount I use and would recommend for the all in one systems. i have done it for ages and it works well then sparge with approx 12litres up or down depending on the grainbill to give 28 ltrs to boil then 3 ltrs boil off to give 23ltrs to the FV after trub loss. I now slightly adjust alot of my recipes as I do 45 min mash 45min boil so boil off is a little less at times. All the figures are approx but will get you somewhere near so that you can adjust them for your own system