Krausen fell already

Made an all grain blue moon clone Sunday. 5lbs 2 row, 4lbs white wheat and 1 pound rolled oats. Og was 1.053. Used 1056 that was taken from a cream ale a week ago and stored in fridge. I warmed the yeast to room temp and pitched it in 68 degree wort after I gave the pail a good shake. About 5 hours later there was some activity in the air lock. Then next morning you could tell there was activity in fermenter from a krausen Mark about 3 inches above the wort. By that same night the airlock had no pressure and it looked like the krausen had all fallen. I shined a light through the bucket to see. About 26 hours after I pitched the yeast. The lid is snapped on tight. There was 250ml of slurry that I pitched to the five gallons. Any ideas why it fell so fast? The temp on fermenter now is 61 degrees.

how much of the 1056 did you pitch? If it was the entire cake from a 5G batch, and it was 62-65* ambient (potentially resulting in high 60’s/low 70’s ferment temp), the fermentation could have easily happened quickly during that time.

As with just about ‘all things fermentation’ though, the only way to tell is to check gravity.