Make sure you attach a blowoff hose when adding or have one already attached. Adding the hops will certainly release some CO2 in suspension. I almost got my teeth knocked out by a 3" SS dry hop port cap at one point after adding the first batch of dry hops to our DDH at Tupps. We would add a bag of hops, wait for the resulting volcano to subside and the pressure to go down, then add the rest. This time I got a false reading on the pressure gauge and went up the ladder to add the second bag. Turns out the blowoff arm was clogged with hops and sludge. Really glad I didn't have my face right over the cap because when I removed the tri-clamp, it exploded off the tank and hit the ceiling with some force - 20 feet above the tank. The worst I got was completely covered with beer and hops, a large amount of cleanup after, and scared to death. The beer turned out fine.Ornlu said:
A significant portion of the haze comes from adding hops during still-active fermentation, so that the yeast eat the hop trub & turn it into disbursed cohumulone (which is very hazy). It's called Biotransformation.
I try to add them about a day after peak krausen, so around 3-4 days after pitching yeast.