Sea water densitometer - Manual detection of water density in sea water samples. Easy to use for quick readings in fish tanks. Helps monitor density and salinity to support stable tank conditions. Aquarium areometer (hydrometer) - Strong wear and break resistance with durable construction. Designed for regular use in aquarium environments and reliable density measurements over time. Aquarium salinometer - Floating design allows placement in any corner of the tank. Automatic temperature compensation and testing features provide professional level salinity readings for aquarium use. Water measuring tester - Wide application range with fast measurements and simple operation. Reliable performance for general water quality testing in marine environments. Practical use scenarios - New marine tank setup: use the densitometer to assess water density, use the salinometer to verify salinity, and use the water measuring tester to confirm overall water quality before adding livestock. - Ongoing reef tank maintenance: perform periodic checks of density and salinity to ensure stable conditions, reducing stress on corals and fish. - Quarantine or portable tanks: place the salinometer in any corner of the tank for quick salinity monitoring during transfers or acclimation, with fast readings and reliable results.