Sera Test GH for the exact determination of the total hardness in fresh or marine water. The test is sufficient for 420dGH. Most ornamental fish kept in aquariums originate from areas with soft water. The total hardness indicates the amount of alkaline earth metals in the water - calcium and magnesium are particularly important in this context. It should correspond as closely as possible to the water of origin of the fish and shrimps being kept. A GH appropriate to the aquarium inhabitants prevents deficiencies and contributes significantly to the health of fish, invertebrates, and plants. The sera GH-Test makes it easy to monitor the total hardness and select fish species that can preferably be kept in the available water. Sera Test GH Total Hardness+ monitor the total hardness (GH) in aquariums and garden ponds according to scientific standards+ allows precise adjustment of the total hardness+ a total hardness appropriate for the aquarium inhabitants prevents deficiencies in fish,