WISRD Research & Engineering Journal

2.5.2 Mixing Seawater We simulate seawater for our tanks using Instant Ocean Sea Salt (Fig. 17) and RO/DI water. Instant Ocean Sea Salt is easy to obtain, economical, and commonly used by hobbyists, public aquariums, and scientific research facilities, as well as Unique Corals, from whom we receive our research corals. See Appendix A for the ingredients in Instant Ocean. Using this salt mix and RO/DI water to simulate seawater is more efficient than bringing in and cleaning ocean water.

Figure 17. Left: Instant Ocean as purchased in bags. Right: Salt transferred to an airtight bucket for storage and scooped out with a plastic measuring cup. The airtight seal is important to avoid humidity affecting the salt crystals, which might cause inaccurate measurements of salinity. To make seawater, we use 2 cups of Instant Ocean for every 4 gallons of RO/DI water, to achieve 1.026 specific gravity. The seawater is made in batches and stored in five-gallon buckets for at least 24 hours to ensure that the salt mixture has completely dissolved (Fig. 18).

Figure 18. Left: Salt added to bucket containing RO/DI water. Middle: Mixture stirred until dissolved. Right: Five-gallon buckets are used to mix and store seawater. Before using simulated seawater, water salinity is tested and adjusted with RO/DI water down to 1.025 as needed; salinity can change if water evaporates from the buckets during storage. Water is then warmed with aquarium heaters (Fig. 19) to match the temperature in the tank.

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