Reef Builderâ„¢ and Reef Bufferâ„¢ may be used together. Use Reef Builderâ„¢ to raise carbonate alkalinity without affecting pH. Use Reef Bufferâ„¢ to raise carbonate alkalinity and pH. Unlike the competition, Reef Builderâ„¢ contains calcium, magnesium, and strontium to compensate for the inevitable loss which occurs when raising alkalinity. It also contains sufficient magnesium to restore magnesium routinely depleted.