Probably very little benefit, as it is not going to host a lot more bacteria that will munch away on the organics in the tank.
What will host more bacteria is
biochar. It has LOTS of surface area and you could really
boost the bacterial count in your tank if all that area was covered with actively metabolizing anaerobes. These products that you can buy at the store to flush down the toilet once a month -- essentially sawdust inoculated with bacteria -- rely on that principle, lots of surface area and some new critters to add to the mix. But that sawdust is itself eaten up in time, and the surface area goes away. Which is where biochar would have an advantage. The rate at which biochar gets eaten up by micro-organisms is in the thousands of years.