Here's a solid example of why messing with pH is a very imprecise thing, and potentially disasterous:
A few weeks ago I started 6 batches:
pH 3.75 -- Cabernet Sauvignon 1 (4 lugs)
pH 3.72 -- Cabernet Sauvignon 2 (4 lugs)
pH 3.77 -- Cabernet Franc 1 (4 lugs)
pH 3.75 -- Cabernet Franc 2 (4 lugs)
pH 4.07 -- Merlot 1 (3 lug)
pH 4.13 -- Merlot 2 (1 lug)
The CF and CS are near the top but within my acceptable range, so I didn't change anything. However, the Merlot are in the danger zone so I eyeballed it, adding 2 tsp tartaric acid to Merlot 1 and 1 tsp to Merlot 2.
Today I filled barrels and took readings on everything. The results are somewhat surprising:
pH 3.45 -- Cabernet Sauvignon, both batches combined
pH 3.77 -- Merlot, both batches combined
The Cabernet Franc was in 4 carboys so I checked each individually:
pH 3.37 -- Bravo yeast 1
pH 3.41 -- Bravo yeast 2
pH 3.40 -- Avante yeast 1
pH 3.36 -- Avante yeast 2
The CS and CF are now in a good place, although any adjustments will be done by taste. The Merlot is on the high side, but again, any adjustments would be by taste. However, I'm making CS and CF heavy blends, so the Merlot's pH may be ignored. Any leftover Merlot will probably be blended into high acid Chambourcin, so it's high pH will be a benefit.
Be very careful of chasing a number, as you may not be chasing what you think you're chasing. And worse, you might catch it!
