Welcome to the hobby! It’s a lot like drinking from the fire hose but very rewarding
Keep in mind nothing good happens from changing parameters quickly for salt water tanks.
I recently changed to a new tank and with new sand/ old live rock it triggered a mini cycle/ can take 2-4 weeks to stabilize again. As others said reusing the old sand there’s a lot of detritus in there that gets put into the water column.
Ugly stage w algae/ cyano outbreaks is reduced with less lighting while the stabilization happens.
The corals/ fish you have are used to the conditions, while new ones won’t be/ can be shocked. You can also ask about the local shop water parameters vs yours for less shock and acclimation.
Keep in mind nothing good happens from changing parameters quickly for salt water tanks.
I recently changed to a new tank and with new sand/ old live rock it triggered a mini cycle/ can take 2-4 weeks to stabilize again. As others said reusing the old sand there’s a lot of detritus in there that gets put into the water column.
Ugly stage w algae/ cyano outbreaks is reduced with less lighting while the stabilization happens.
The corals/ fish you have are used to the conditions, while new ones won’t be/ can be shocked. You can also ask about the local shop water parameters vs yours for less shock and acclimation.