Aquarium Systems SeaTest GH Hardness – 40 Tests General hardness (GH) indicates the quantities of magnesium and calcium salts dissolved in water. The recommended level is between 6 and 20°GH in freshwater, depending on the species kept. Use this Aquarium Systems SeaTest to make sure your fish can thrive in the best possible conditions for their species. For freshwater only. 1 drop = 1°GH. Changes the colour from purple to blue. 2 x 10 ml to test 480°GH.
