Yeast Cakes: 1 smooth, 1 lumpy - why?
As a water chemistry experiment, I brewed 2 batches of a London Pride clone using the same grain bill, hops and yeast. They were fermented side by side under my stairs which is a steady 68F.
After I racked both batches this weekend, I noticed a big difference in the yeast cake and the krausen level in the fermentors. (see images attached). Anyone know which, if any, of the following could have caused this:
1. Smooth Yeast Cake:
40% water from my faucet and 60% distilled water.
Faucet water is v hard (220 ppm as CACO3) and high in Alkalinity (200 ppm as CaCO3).
4g gypsum (1tsp)
2. Lumpy Yeast Cake
100% water from the faucet
Both appear the same, although 2 has a slightly higher alcohol content (5.4 vs 4.7 abv)
Taste: 1 is a lot smoother and maltier. 2 tastes good, but has a slight harsh bitterness to it (too much gypsum?)
Both will be drunk this July 4th, I dont doubt that, but any ideas on what causes the yeast cake to be so different?
Reason: added attachments