Kolsch Not Finished

[Brett3rThanU]

I brewed a Kolsch (10 gallon batch) with the recipe below at about 57F.

15 lb Kolsch Grain (Similar to German Pilsner)
3 lb White Wheat Malt
2 lb of honey
Hallertauer hops

So I brewed the above recipe and divided the 10 gallons into 2 separate primaries. The OG was 1.061 (overshot) Previously made 2 1 liter starters from 1 package of Wyeast #2565 and put one liter in each primary. Unfortunately I didn't get the amounts even in each primary and ended up with 4.5 gallons in one and 5.5 gallons in the other. The owner of the shop told me not to expect the krausen to fall completely with this yeast and trust the air lock instead, but I still let it sit at 57F in the primary for 2 weeks. I then racked to the secondary and took gravity readings. The 5.5 gallon batch was at 1.018 and the 4.5 gallon batch was at 1.013, high, yes I know, but I racked anyway. Why would the gravities be different? Anyway, I took another reading today (4 days later) from the secondary and the 5.5 gallon is at 1.015 and the 4.5 gallon is at 1.010. I know I probably should have waited to go to the secondary, but I didn't so it is what it is. Should I give it a few more days before I cold crash the secondaries? That 1.015 still seems kind of high to me, but calculating the attenuation it's 75% which is spot on for this yeast. Anyway, my plan when bottling comes is to mix both batches together for bottling that way they all taste the same.

1) Why did the FG come out different? I guess it could have been aeration, quality of the starter, etc...
2) This happened to anyone else?
3) Should I wait to cold crash to see if it drops more?

 

[skiwithg]

I would leave it there until you get the same gravity readings per secondary for 2 or 3 days in a row. Activity in the airlock is an imperfect method to determine if fermentation is complete. They can bubble forever as CO2 dissipates or they can never bubble if there is a leak in the stopper.

IME, that yeast is real, real slow to drop.

As to why the larger batch is slower, I'm speculating that if the same amount of yeast was pitched to each primary and all else was equal, there is just more sugars for the yeasties to eat in the larger batch. Maybe its possible that the wort was stratified before racking to primary, so one primary has more fermentables than the others. I'm interested to hear what others think.

FWIW, I usually see 75% to 80% apparent attenuation with WY2565.

I only brew 5 gallon batches, so I don't have any thing to offer on the 2nd point.

Blending both before bottling seems like a fine idea.

Cheers,
Glenn