Measurement Discrepancy

Don't be worried if you don't get the following. Just read the last para of this section.

The numbers that Nuff is referring to would be VFO and VAW.

Volume of Ambient wort = Volume at Flame Out less shrinkage from coolina (about 4%).

Volume of Ambient Wort also equals Kettle to Fermentor Loss plus Volume into Fermentor.

So on one hand, your numbers are saying VAW = 12.5 x 0.96 = 12 litres, whilst on the other hand they are saying VAW = 9.0 + 1.8 = 10.8 litres. So we have a 1.2 litre discrepancy in your actual measurements. My guess is that your VFO measurement was wrong as they are often very hard to measure accurately with all hte steam etc so...

Let's assume your VAW was 10.8 litres. Let's see how your numbers add up...

Your estimated metric gravity points for the brew were about 500 (I need file to be exact.)

Actual VIB * GIB points = 16.0 * 31 = 496 metric gravity points. (That's a good match).

Actual VAW * metric gravity points = 10.8 * 38 = 410 metric gravity points (This is way below the estimate and should match or be close to the above figure. Even if we go for the VAW based on your flame-out measurement, we still only get to 456 points).

What the above all means is that when you look at your BIABacus file in Section P, you are going to find a large discrepancy between EIB and EAW whereas they should be the same in theory. (In practice, due to difficulties of measurement, they rarely match but they should generally be within 5% of each other).

So the first thing to recognise is that there is some sort of measurement error going on which you'll hopefully find is just an aberration on this one brew.

Evaporation

As you said, this is probably the last major cause of your low original gravity. Assuming you have a good rolling boil, here is what I think is happening...

Your batch size is really small compared to your kettle so I think it is possible that the auto-estimate for your kettle is not working well. I would say that a lot of your evaporation actually runs down the side of the kettle back into the wort so your evaporation rate is far lower than the auto-estimate.

Look back over what numbers you have for your brews and see if you can determine what your average evaporation rate is. Use the lowest of these and type it into Section W for your next brew. Or try a larger batch size of around 20 l VIF.

Drink up!
PP

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Can't see the mistake that explains the oddness drt. I was hoping that your mistake may have corrected the discrepancy between VFO once chilled (12.02) and your actual VAW (10.8) - see section L. ANyway I am assuming the VFO number was an error.

I see though that I made an error. In my last post for metric gravity points into boil, I should have had 16 * 26 = 416. Correct that for shrinkage and it comes to about 400 points which is very close to the 410 points you had of ambient wort. What does that tell me?

It tells me that your Efficiency into Boil and Efficiency of AMbient Wort are confirming each other. You'll see that in the BIABacus file as well... 69.4% versus 71.2%.

The good news is that your measurements confirm each other. The bad news is that they also confirm that the efficiency problem still exists and evaporation has nothing to do with it . (Mind you do those evap corrections I mentioned on your next small batch in the big kettle.)

Now, earlier on we talked about pH but, on reading back through, I can't find any result on this. Does anyone else all-grain around you? Do you know if there are water problems in the area? Did you get to check the pH?

Wow! Don't think I've ever come across an efficiency problem before that has been so hard to solve.


PP

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Re: Low Sugar Yield

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That pH of 6.0 isn't enough to explain the large discrepancy but find out what the Sydney troops are doing and so likewise. As lumpy says, acidulated malt would be easier than using crystals or dark grains. You can even use a bit of white vinegar to lower your pH as yours is pretty close anyway. Another choice is citric acid available from your supermarket.

Fingers crossed for the next one

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Good to see you getting closer drt ,

I'll go through some of the things above but before that, there is one more possible cause, especially since the grain is crushed, and that is moisture content. Let's say you buy one kilogram of grain and it is perfectly dry. Imagine if over time it absorbed 10% moisture. The grain will now weigh 1.1 kilos and so when you weigh ouyt your grain bill you will inadvertently be using less actual grain.

If you have some good scales, you can weigh out your grain in a pan and then dry it in the oven and weigh it again afterwards. You really should be getting about ten percent better than what you are getting at the moment.

On your next brew, use a different brand base malt and get the grain crushed in front of you .

....

Using more water does not affect efficiency. If anything, it will improve it as you are 'washing' the grain in more water. If you put two teaspoons of sugar in half a mug of coffee, it will taste really sweet. Put it in a full cup of coffee and it will taste less sweet but there are still 2 teaspoons of sugar there. Efficiency is about the amount of sugar in the wort. A half mug of coffee with two teaspoons is just as 'efficient' as a full mug of coffee with two teaspoons of sugar. Just as...

10 litres of 1.050 wort is as efficient as 20 litres of 1.025 wort.

As for your evaporation rate, go to Section X and change your evaporation rate there. Don't change the boil time.

I hope you can try out the oven experiment! And thanks for keeping us updated ,
PP

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