Seachem Replenish is designed to increase the GH of freshwater aquariums. Like KH, GH is a measurement of water hardness. Where KH (carbonate hardness) measures the concentration of carbonate in the water, GH ( general hardness ) measures the concentration of calcium, magnesium, sodium and potassium.
Like pH and KH, different freshwater fishes have their own preference of GH. And normally they are able to adapt to a wide range of GH provided that they are slowly introduced to them. That being said, keeping them in their proper GH level will ensure a healthier and more vibrant fish.
Osmotic Shock
When fishes are suddenly introduced to water that has a very different GH level, osmotic stress will occur. This is where a large amount of water will enter the fish cells when suddenly introduced into water with much lower GH or exit when suddenly placed in water with much higher GH. This will in turn cause the rapture or collapse of cells. Osmotic shock can be fatal therefore it is important to match GH when introducing new livestock into an aquarium. Although most local fishes are kept in the same GH but there are some more exotic species that might have been kept in different GH. Certain live barrier fishes such as guppies might also have a different GH level then most common fishes in Malaysia. Freshwater shrimps will also need proper GH care as they can be very sensitive.
Low GH but not zero GH
There are many species of common freshwater fishes that prefer soft water. But this doesn’t mean that they will thrive in water devoid of GH. For example discus prefers soft water but when the water runs out of minerals they will have ill effects such as loss of appetite or discoloration. Discus will actually do better and breed more effectively in water with GH of around 1-3dGH.
No fish can survive without any minerals in water. And therefore, it is very important to add GH to your aquarium if reverse osmosis water is being used.
How to use
Each cap or 5ml of Seachem replenish will increase 1dGH in 40L water. Adjust the hardness of GH according to your fish needs. If it’s a community fishes aquarium, pick a middle ground. During water changes, dosage calculation should be based upon the amount of new water that is being added into the aquarium.