Seawater Hydrometer Aquarium Water Concentration Aquaculture Salinity Meter Specifications: Insert the hydrometer to the water tank or fish pond below 15cm until the water overflows the baffle. When the water reaches the full state, take out the hydrometer and place it on a horizontal surface. Bubbles attached to the needle will result in inaccurate readings. Carefully tap the hydrometer to vibrate the adhering air bubbles. Read the specific gravity according to the inner scale and read the salinity (PPT) according to the outer scale. It is recommended that the seawater of the seafood pool be between 1.020 and 1.023, which is within the safety line. Square type: specific gravity range: 1.000-1.030, salinity range: 0-40. Rinse with water after each use. Type: Seawater Hydrometer Material: Plastic Specific Gravity Range: 1.000-1.030 Salinity Range: 0-40 Size: 9cm x 12cm x 1.5cm/3.54" x 4.72" x 0.59" (Approx.) Notes: Due to the light and screen setting differe