ok, about the Lr, remember that livgerock is infested with M.I.C.R.O.S.C.O.P.I.C. ORGANISMS, that means u cant see them;YOU NEED A MICROSCOPRE lol. But that doesnt meant hat u wont have some critters that u can see down there, its possible, but dont count on it. No, it wont matter if you add LR of a diff kind tomorrow, but remember, you must cluture it to ur water from the point that u go this LR, not the other...or soemwhere in between., just set ur cycling clock back a couple days, lol.