Since I'm using RO water I have had to manipulate my water to make it suitable for fish. Here is what I have learned about GH/KH along the way:
GH (general hardness) relates to the amount of Calcium & Mangnesium in your water.
Can be raised using (CaCO3)Calcium Carbonate which is simply shells, Coral Sand, Chalk, or Lime. If used it will also raise your KH.
Can be raised using (MgSO4) Magnesium Sulphate which is Epsom Salts and will not raise KH.
Freshwater combo mix = (3 parts CaCo3) with (1 part MgSO4) Commercially sold as DOLOMITE
Most fish do well in a GH of 6-8
Some people prefer CaC12 Calcium Chloride which is road salt but I don't know where to get it and I know nothing about how it is used in aquariums.
Can be reduced by dilution with RO water
KH (Carbonate Hardness) also called buffering capacity
Can be raised using (K2CO3) Potassium carbonate or potash which will not raise Ph and the potassium is good for your aquatic plants.
Can be raised using (NaHCO3) Sodium bicarbonate or baking soda but it also raises Ph and it breaks down quickly which causes Ph swings that could kill your fish. Here is a link to a calculator that will tell you how much your Ph will rise by using baking soda in your tank http://dataguru.org/misc/aquarium/calKH.asp If you use this calculator you should know how much actual water is in your tank "not what it said on the label when you bought it". Once you add decorations and gravel your tank has less water than stated.
Can be reduced by boiling water.
Can be reduced by water surface agitation.
Can be redced by nitrifying bacteria.
GH (general hardness) relates to the amount of Calcium & Mangnesium in your water.
Can be raised using (CaCO3)Calcium Carbonate which is simply shells, Coral Sand, Chalk, or Lime. If used it will also raise your KH.
Can be raised using (MgSO4) Magnesium Sulphate which is Epsom Salts and will not raise KH.
Freshwater combo mix = (3 parts CaCo3) with (1 part MgSO4) Commercially sold as DOLOMITE
Most fish do well in a GH of 6-8
Some people prefer CaC12 Calcium Chloride which is road salt but I don't know where to get it and I know nothing about how it is used in aquariums.
Can be reduced by dilution with RO water
KH (Carbonate Hardness) also called buffering capacity
Can be raised using (K2CO3) Potassium carbonate or potash which will not raise Ph and the potassium is good for your aquatic plants.
Can be raised using (NaHCO3) Sodium bicarbonate or baking soda but it also raises Ph and it breaks down quickly which causes Ph swings that could kill your fish. Here is a link to a calculator that will tell you how much your Ph will rise by using baking soda in your tank http://dataguru.org/misc/aquarium/calKH.asp If you use this calculator you should know how much actual water is in your tank "not what it said on the label when you bought it". Once you add decorations and gravel your tank has less water than stated.
Can be reduced by boiling water.
Can be reduced by water surface agitation.
Can be redced by nitrifying bacteria.