Old rock/new rock, bacteria will still end up carrying over populate and multiply. The more you can feed bacteria, the better the system with bacteria population.
Why is a carbon source needed for feeding bacteria. The answer is pretty plain and simple. Ever been sick for a long duration? The foreign bacteria in your body which gets you sick will feed off any sugar proteins (carbon) that you introduce into your system. The less intake of a carbon source the less time frame you are on being sick.
Same theory applies here. So if you want to keep those little guys happy and populating quicker, feed them a carbon source.
Why is a carbon source needed for feeding bacteria. The answer is pretty plain and simple. Ever been sick for a long duration? The foreign bacteria in your body which gets you sick will feed off any sugar proteins (carbon) that you introduce into your system. The less intake of a carbon source the less time frame you are on being sick.
Same theory applies here. So if you want to keep those little guys happy and populating quicker, feed them a carbon source.