Yes, but if your roommate is setting up a reef, he's going to want to test for calcium, alkalinity, magnesium, and salinity prior to using it. I use Instant Ocean, but it is usually deficient in calcium and magnesium, with some of the more recent batches having more of those than others. He may or may not have to boost them, but should test each salt batch (box/bucket/bag) after mixing prior to adding to the tank. Your FOWLR won't be as critical, but would still benefit from having balanced calcium and alkalinity levels. You two could split the difference on the chemicals, which are cheap.