AG never finish attenuating

[HopsAreGood]

Because it is extra stuff that has a taste that goes into the beer. I know of cases, where mysterious off-flavours were hunted and hunted and not found... until they ditched the yeast nutrient.

Malt is basically really rich in nutrients, and although beer yeasts are a bit of spoiled character, compared to not minding wine yeasts, they still have everything they need within the wort already present. A healthy pitch rate and fitting temperatures is everything that is needed.

One could argue that kveiks are a little exception, as they have eveolved within higher gravity wort, but from my own experiments, I must say that at least lutra performs very well in low gravity worts (1.03) without any extra nutrients. I had the same result with voss in "normal" gravity wort (around 1.05).

So the takeaway is: Do not use stuff in your beer that is unnecessary because it will somehow affect the flavour. if it is in there, it will be also in the flavour, maybe underneath the taste threshhold if you are lucky, but if unnecessary from the beginning, why take the risk?

I don’t know man. I understand your overall point but I’ve used the wyeast beer nutrient for years and never noticed anything negative from it. Perhaps I’ll try a batch or two without it but I’d be shocked if I noticed a difference. I dilute a tiny amount of it in a tiny amount of water, and then add it with about 10 minutes left in the boil. I really can’t see how it would contribute to off flavors in the final beer, but I guess I can’t really say for sure.

 

[madscientist451]

Any chance that the grainfather is heating some of your mash higher than your desired mash temperature?

 

[BrewnWKopperKat]

On the side topic of yeast nutrients, this Zinc and RO Water | Bru'n Water may be of interest.

 

[MicroMickey]

Sounds to me like you either don't aerate your wort or don't aerate enough. Yeast really needs O2 in about 8 - 11 ppm which takes a lot of shaking.

 

[BrewnWKopperKat]

OP stated they were using US-05. Fermentis, in their Tips & Tricks brochure (page 22, link to download) mentions that there is no need for aeration when following their processes (initial pitch, either dry or re-hydrated).

That being said, if one is re-pitching US-05, it would seem reasonable to apply 'best practices' for liquid yeast strains.

 

[madscientist451]

Yeast really needs O2 in about 8 - 11 ppm which takes a lot of shaking.

The above is one of those brewing myths that just won't die. Brewers large and small made beer for centuries without adding oxygen. You don't need to shake your beer or add oxygen. Put a funnel in your carboy and dump your wort in. A healthy, active and proper amount of yeast will consume fermentable sugar.

 

[hotbeer]

How did the FG get determined? A SG reading after a prescribed time period. Or two identical SG's three days apart? Or some other?

Possible the the fermentation was still going on and just never finished.