You want everything in your tank when you cycle. Like rocks, sand, heater, poweheads. Lights aren't needed. Petco and petsmart are a no no. I used something like
For my rock. There are more expensive options also for sure
Petsmart does not carry marine fish. Petco does and I had one local that was as good as any LFS, got familiar with the young lady running the marine section and found she was very knowledgeable about reefs. The animals were well cared for and I still have many corals and fish from her 6 years later. So don't say petco is bad when some are actually good. Well needless to say she got burnt out from the other staff who would not take care of the animals like she had asked and quit working there. After that they went downhill fast and my last purchase was a yellow tang 4 years ago skinny with shredded fins, I had some words with management and got her for $10. Now she is fat and happy, never got sick. Now they have a private contracter to manage the marine animals and now the tanks looks amazing. I just may buy there again.