hey freshyfresh
you can add the water right now if its cold, but once u start putting corals in i'd suggest getting the water closer to room temp of that of ur tank. I'd go out to the LFS or online and buy a small powerhead(20$) and small heater(10$) and make ur water a couple days before your going to do ur water change. I would NOT take ur heater outta of ur tank, they are very sensitive and cant break. (if u take from hot to cold) .. When you say target ur rocks, do u mean when u add the water? if so then yes, it wont stirr sand up- but u should also use a power head or when u syphon water out to blow crap off the rocks. If u cant read all ur rocks dont worry bout it. get as much as you can. its like freshwater water changes , but dont forget the salt
you can add the water right now if its cold, but once u start putting corals in i'd suggest getting the water closer to room temp of that of ur tank. I'd go out to the LFS or online and buy a small powerhead(20$) and small heater(10$) and make ur water a couple days before your going to do ur water change. I would NOT take ur heater outta of ur tank, they are very sensitive and cant break. (if u take from hot to cold) .. When you say target ur rocks, do u mean when u add the water? if so then yes, it wont stirr sand up- but u should also use a power head or when u syphon water out to blow crap off the rocks. If u cant read all ur rocks dont worry bout it. get as much as you can. its like freshwater water changes , but dont forget the salt