I always cycle my tank with lights on because eventually you’ll turn them on anyway. For diversity, there are many strains of bacteria, algae, and other micro fauna that will make their way into our tanks. If you’re using a complete dry rock start with bottled bacteria, there isn’t much competition and usually some type of ugly algae can take hold. It’s common to see something like a brown dusting of diatoms that seem to drive most newer reefers crazy.
For me, I keep my rocks from previous tanks and add them to my new start ups to keep whatever bacteria and other things are growing on it. Worms, pods, sponges, coralline and so forth. They do help to skip over the ugly stage or avoid it largely. In our tanks (and the ocean), every creature is fighting to be king. So keeping biodiversity allows them to compete with each other.
Adding in corals from other peoples tanks will start to add more biodiversity even if you dip them which I highly recommend. But useful things like coralline algae can come in. Beneficial bacteria. But also pests can be added in. But this is the “fun” part of the hobby, so to speak.
(j/k)
