Stout hasn't reached final gravity

[Hazelwood Brewery]

I can't see that grain bill getting within a bulls roar of 1,052 in 23 litres.

I think this is quite possible, I regularly get 23 litres at between 1.048 and 1.050 from

3.6Kg Maris Otter
300g Oats
200g Light crystal
100g Tortified wheat

The OP is mashing 800g more malt than me so you would expect a higher gravity than I achieve.

I think this efficiency is a factor of how fine the grist is and how long the mash is because I’ve also had the situation where my gravity is waaay lower than it should be and I’ve had to mash for hours to get the gravity near to where it should be - reflecting that I did think there was not a lot of “flour” in the grist as I mashed it in.

 

[Hazelwood Brewery]

I don’t think I saw any mention of water treatment or mash pH in this thread. Mash pH can affect enzymatic efficiency so could in theory affect fermentability of the wort?

 

[Larse]

I don’t think I saw any mention of water treatment or mash pH in this thread. Mash pH can affect enzymatic efficiency so could in theory affect fermentability of the wort?

I didn't take the pH, possibly something I should start doing, but I did treat the water. My water (well water) has a pH of 5.3 and very little solids and no chlorine.

So for this I added two tsps of Gypsum and 1/2 tsp of Potassium Chloride. Then boiled and cooled. Procedure from The Big Book of Brewing.

 

[Hazelwood Brewery]

I didn't take the pH, possibly something I should start doing, but I did treat the water. My water (well water) has a pH of 5.3 and very little solids and no chlorine.

So for this I added two tsps of Gypsum and 1/2 tsp of Potassium Chloride. Then boiled and cooled. Procedure from The Big Book of Brewing.

Your source water pH suggests low alkalinity surface water and you’ve added plenty of calcium which should result in a lower mash pH - which if I remember correctly would favour a more fermentable wort.

I might be barking up the wrong tree but was worth a thought.

I think taking pH readings is worth doing because it can help diagnose/explain issues.

 

[Larse]

I never took pH readings because I never had a problem with fermenting out until now. It was one of the possible causes in my own mind when I posted here, but you're the first to mention it. I have pH papers, so I'll start with those and see what they tell me.

On balance though, I think under-pitching was probably the root cause.