Idiots guide to hydrometer use please

[Rogermort]

Been brewing two years now and I'm never certain when and how often I should be using the hydrometer during the brew day.

Last couple of brews everything has gone to plan but I got in a right mess today, took a pre boil reading which suggested I was missing the intended gravity by 10 plus points. Dialled in intended gravity and actual to BeerSmith, it suggested I needed to chuck 1.3 kilos of dme into the kettle. Only had 630 grams so chucked that in.
Volume came up short by a litre but by the time I was ready to pitch the yeast starter the OG was way higher than expected. It's going to be a strong one!

I am adjusting gravity readings for temperature but I'd like an *****'s step by step to when to take readings that I need to react to.

I'm fly sparging by the way and I think the original missed gravity was down to a faster than usual sparge.


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[Hoddy]

Are you cooling your wort to 20oC before measuring? Or are you applying a temp correction factor?

My rule for testing is

Post mash
Post sparge
Mid boil
End of boil

I use beersmith and the predicted pre boil and post boil readings and put in a midway reading for the mid boil. That should work perfectly and give you an early warning if your missing targets.


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[Rogermort]

Temp correction using the BeerSmith calculator.

Is your post mash reading of the first running at Vorlauf?

Is the post sparge reading taken from the final volume in the kettle while heating but before reaching the boil?

End of boil? Straight at flame out?

Another when the batch has been cooled in the FV but prior to pitching?


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[chuffer]

I just do it the once, at room temp just before I pitch the yeast, to get the OG....oh and I check the runnings dont drop below 1.008 when I'm at the end of sparging

 

[blawford]

I just do it the once, at room temp just before I pitch the yeast, to get the OG....oh and I check the runnings dont drop below 1.008 when I'm at the end of sparging

Is the 1.008 figure temperature corrected?

 

[MrN]

I find the most useful is pre-boil (post mash/sparge, once everything's in the kettle) because, assuming you know your boil off rate, you can predict what your og will be and have plenty of time to react e.g. adding dme to raise gravity or adjusting for hop utilisation.

To speed it up a bit I tend to keep a small metal saucepan in the fridge and then take a sample of hot wort out the kettle, put it in the cold pan and then set it in some cold water. This gets it cool enough petty quickly.

Of course the other important one is to check the og pre-pitching. If I'm way over I'll add some soft bottled water to dilute.

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[chuffer]

Is the 1.008 figure temperature corrected?

yeh it should be! Can't say I always have though, my runnings normally come out at around 65 0C so at that temo 0.99 would be the magic figure according to this:

https://www.brewersfriend.com/hydrometer-temp/