I thought I'd add this topic to accompany Blue Bolts great thread on correct ratios and dosing of Calcium and Magnesium. http://www.shrimpkeepersforum.com/forum/showthread.php/4383-GH-Ca-MG-Ratio
So why is Calcium & Magnesium important to both aquarist who keep fish and those of us who keep shrimp? CALCIUM SULFATE:
CaSO4 Calcium sulfate in your aquarium will keep a more stable electrolyte balance (for osmotic function), while magnesium is another important element that works with calcium.
A proper amount of Calcium and Magnesium in your aquarium will affect your shrimp or fish health positively, including fish from low pH environments such as Apistos, Discus or German Rams
Magnesium and Calcium have been shown to increase resistance to degenerate diseases by lowering the acidity in the body. This will help with prevention of ich and fungus in your fish.
Calcium also helps in healing and stress, and without proper calcium levels healing may be difficult or impossible. Calcium is also important and has been shown to both prevent and treat Hole in the Head disease common to cichlids (also referred to as HITH).
The addition of antibiotics (such as Tetracycline) will lower calcium absorption, while the presence of correct amounts of calcium in the aquarium water will considerable reduce the toxic side effects of Malachite Green which is why a GH (for freshwater calcium measurement) of 100 ppm (for freshwater) is SO VERY important to ich treatment.
Calcium can adversely affect the kH of a discus aquarium when combined with sodium carbonates or bi carbonates, which is generally kept at a pH below 6.5. Not that calcium has a direct impact on raising or lowering kH, but that it assists in buffering the water to avoid swings in kH and thus pH.
I have successfully used sources of calcium in discus (low pH) aquariums by using a mix of RO (Reverse Osmosis) water and tap water (dilution will vary depending on your tap and tank water parameters). Then add electrolytes/mineralsto the RO water and add peat to the filters. This method has been used successfully with discus and calcium added with no pH climb.
The peat will leach minerals into the water that will bond with the Carbonate thereby preventing it from bonding to the “H+†ion, thereby lowering KH and subsequently pH. This is a good method for planted tanks as the nutrients can also be used by plants.
Calcium sulfate is soluble in water. However, it's solubility is extremely poor. Only a small amount will dissolve, and this will take place extremely slowly over time. To improve solubility, use a mortar & pestle to crush into a fine powder before adding to water.
Calcium is particularly important to the average shrimp and invertebrate keeper.
Calcium plays a huge role in Osmoregulation. And as such plays a big role in assisting the shrimp's moulting cycle.
Ever have shrimp die during a failed moult? Check the Calcium levels in your water. MAGNESIUM
Magnesium is important for proper osmotic functions in fish and invertebrates. Magnesium is essential for Calcium assimilation, so when magnesium levels are low, the calcium supply becomes exhausted. For this reason, Magnesium is better added in the proper balance with calcium (which both are essential to each other for proper utilisation).
Epsom salts that contain magnesium sulfate, are best used for therapeutic reasons such as to aid in flushing the system as it aids in and speeds osmotic function, and helps to move fluids out of the body.
Sulfates, one of the major components of Epsom Salt, have been shown effective in improving nutrient absorption and toxin elimination.
Magnesium, the other major component of Epsom Salt, plays a role in the activity of many enzymes.
Also note that Epsom salts (MgSO4) do NOT evaporate or decompose, so only add more after water changes. Where to Buy:
Calcium Sulfate CaSO4 can be purchase from
Aqua Green
Aquotix online store (aquariumonlinestore.com.au)
Ace Chem (http://www.acechem.com.au) - bulk orders
Magnesium Sulfate can be purchased from
Aquotix online store (aquariumonlinestore.com.au)
Bunnings (Manutec Epsom Salt)
Big W (Manutec Epsom Salt)
Ace Chem (http://www.acechem.com.au) - bulk orders
If there are more sources, let me know and I'll update the list.