sera guide - Marine aquariums

32 It is best to prepare the marine water in a suitable and sufficiently large container, e.g. a rain barrel made of plastic (as it is corrosion proof). Follow the instructions for the sea salt you use. The nitrate level should be below 10 mg/l (ppm), phosphate and silicate should not be detectible. Check the water with the sera phosphate-Test, the sera silicate-Test and the sera nitrate-Test for being sure. You can also ask your local water provider for the measured values or look them up on the in- ternet. The salt is now by and by added to the water while stirring, until you achieve a salinity of approx. 35 per mille (i.e. 35 grams per liter of water). This corresponds to a density of 1.023 g/cm³ at approx. 25°C (77°F). De- pending on the setup, you will require about 130 – 150 liters (34 – 40 US gal.) of marine water for a 130 liter (34 US gal.) aquarium. You will need about 5 kg (1.1 lb.) of sea salt. The marine water should be agitated by a pump in the container and aerated for about 24 hours. The water will then appear perfect- ly clear. 5.2 How to prepare marine water The sera marin hydrometer is put into the aquarium or a bigger glass filled with the wa- ter which should be tested, in a manner that it can float freely. The hydrometer will be im- mersed the deeper, the less salt there is in the water. It will display the density of the wa- ter on the integrated scale. The density should be 1.022 – 1.024 g/cm³ at approx. 26°C (79°F) in aquariums with invertebrates. If necessary, add more salt or dilute with con- ditioned water. However, the marine water is not put into the aquarium yet. 5.3 How to measure salinity Density Salinity Salinity Salinity at 33 ‰ 34.5 ‰ 36 ‰ 16°C 1.025 g/cm3 1.026 g/cm3 1.0265 g/cm3 20°C 1.0235 g/cm3 1.025 g/cm3 1.0255 g/cm3 25°C 1.022 g/cm3 1.023 g/cm3 1.024 g/cm3 28°C 1.0215 g/cm3 1.0225 g/cm3 1.023 g/cm3 30°C 1.020 g/cm3 1.0215 g/cm3 1.0225 g/cm3