I fermented 25 gallons of Merlot must and everything was cooking along great but when it got to 7 Brix it slowed to a suggish halt. I reintroduced a couple gallons of freshly fermented must, put in some energizer and things cranked back up. Now it has reached 7 to 6 Brix again and slowed down to barely a bubble. When it reached 7 the first time I also added MLB. My ph is 3.8, my acid is ok, I don't have any off smells and the temp is hovering around 72 degrees in a 75 degree room. I am at a loss.