The metabolism of oceanic life is pretty slow... a week w/o anything but target feeding those sun polyps(other non-photosynthetic critters, too). Everybody should be good. To drop ca, raise alk slowly... they'll balance. You can put the halimeda in the fuge, too. As for know-how... lots of reading and sharing info on sites(none as great as ours!!!). I feed my system 4 times per week(Mon, Tues, Thurs, Fri) with 1/2" cube square of "fish mush"... seek out www.littlereef.com for more info. After lights out, I feed phyto foods (a few drops only...concentrated) on Mon, Wends, and fri.