The 28-year-old South African-born spinner took seven for 18 as he claimed the wickets of Michael Burgess, Sam Hain, Will Rhodes, Liam Banks, Alex Thomson, Henry Brookes and Jeetan Patel, with Leicestershire routing Birmingham by 55 runs.
"It will take a while to sink in, I honestly didn't know six wickets was the previous record," Ackermann said.
"It was the first time it has turned at Grace Road for years, I managed to use my height to get a bit of bounce too, and it helped they kept trying to hit me with the turn over midwicket, which was into the wind.
"I'm really pleased for our home crowd, they turned out again after seeing a couple of heavy defeats and they deserved to see the sort of performance we're capable of."
Ackermann, an all-rounder, said he had been working hard on his bowling over the winter while playing for the Warriors in his homeland, and the rewards were seen with his maiden first-class five-wicket haul in Leicestershire's opening county game of the season against Sussex.
Now his form has helped Leicestershire to three wins from four in the Vitality Blast, overcoming a slow start in the competition.
"Hopefully we will take that confidence into Friday's match against Northamptonshire," Ackermann added.
"They're a side with a good record in recent years in the competition and they're coming off a good win themselves, beating Durham at home, so it won't be easy and we'll have to be absolutely on our game.
"But confidence is important and after a slow start we've shown we can beat anybody. If we keep playing with that belief and execute our skills we will put ourselves right into the picture."
