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The Point Of Diminishing Returns

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Yob

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Its a statistic Im aware of, the bigger the grist, the less the eff.

but why? is it a system dependent thing? How is it overcome?

Im not unhappy with my system and I make it work for me.. today I reduced my eff. 'on paper' from 75 to 65 with a target OG of 1.075 and got a 1.072 so pretty close 'by eye' (bigger grist than normal)

It makes me wonder if I changed my MT for a bigger one and re built my manifold to suit can I make a difference there?

What are the factors that influence this? these days Mash PH and water chem is solid.. (at least as I understand it) where else do I look??

I fly sparge and was at 1015 when at boil volume so what was 'converted' was extracted.. well by the numbers anyway.. Im a little confused here.

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Markbeer

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I think chanelling is a major factor in any system. The larger the grist the more like chanelling will occur that will not rinse all the grains properly. Gives the sparge water more incentive to find the path of least resistance.

I can't remember where I read it but someone tested their mash tun for channeling by using dye. I can't even think how this would be done without a clear mash tun.
 

Wasabi

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Its a statistic Im aware of, the bigger grist, the less the eff.

Sorry, can you clarify what you mean?

The bigger the grist as in particle size or in amount?

B.
 

Yob

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Optimum for my 44 willow is about 4-6 max kilo, anything over that and eff starts to drop off, today for example was a grist of 7ish kilo, eff dropped my usual 75 to 65ish.
 

Wasabi

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He means the amount, the more crowded the less love
Ah ha. That makes more sense...sorry its late here in Auckland and I really should be asleep....

Though I don't think there is a negative correlation between grist bill size and efficiency. Its pretty must mostly related to mash tun/lauter tun design, how modified your malt is and how well your malt is ground.
 

Acasta

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Yob, I believe it's due the the ratio of grain to water, in particular the sparge liquor/grist ratio will be lower. Comparing a smaller and larger grist, the ratio of water (pre-boil volume) to grist is different, and therefore with a bigger grist you get a weaker sparing "rinsing" effect and thus collect less sugar into your kettle.

A way of over coming this would be to increase the amount used to sparge and increase the vigour and length of the boil time to reduce the wort to the appropriate batch size. However, if you are running gas is the 2hr boil time worth the extra bit of grain?
 

Yob

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Ha! No, not at all and at the end of the day I really dont mind throwing extra grains at it but it's just one of those things niggling away at the back of my mind. Its the mechanics of it I just dont fully understand.. and nor do I to make beer thankfully :rolleyes:

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Acasta

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haha. I try not to, but at the end of the day I always like to see some good numbers!
 

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