I have read in many places about the use of Plaster of Paris as a calcium source for both ponds and freshwater aquariums (I too have used this many years back when old timers in the hobby suggested its use for ponds to me), however with the exception of a calcium emergency (or possibly to absorb pollutants in a pond in bulk, which I have used Plaster of Paris for); Plaster of Paris is not the same as products such as Wonder Shells or Sealab blocks. My own years of use have shown me the vast difference in fish health and vitality.

In this article I will hopefully explain this a little more scientifically.

PLASTER OF PARIS:

Plaster of Paris is manufactured by heating gypsum at 120o - 160oC. When Plaster of Paris is mixed in water it dehydrates and form dense matrix of gypsum crystal.

Here is a list of ingredients of Plaster of Paris:

*CaSO4 , 1/2H2O: 97.97%

* SiO: 0.94%

* Al2O3: 0.69%

* Fe2O3: 0.28%

* MgO : 00.12%

What I see here is some Magnesium, Iron, Sulfur, Aluminum, Silicone and mostly Calcium.

Where is the Strontium, the Sodium, Potassium and more? These ratios are also NO WHERE near correct for proper assimilation.

This is not to say that products such as Wonder Shells or Kalkwasser are also spot on in these ratios, however they are much closer than this (or at least Wonder shells are). This also why Marine Buffer by Sea Chem is better for KH control as the proper ratios are applied in this product.

Plaster of Paris is a poor choice for GH or Calcium as Calcium needs to be in the proper ratios with other elements such as Magnesium to be utilized by aquatic life (such as osmotic function).

PROPER OCEAN CHEMICAL ANALYSIS:



By contrast here is the chemical composition of the ocean as a percentage:

Chloride- 55.03%

Sodium- 30.59%

Sulfate- 7.68%

Magnesium- 3.68%

Calcium- 1.18%

Potassium- 1.11%

Bicarbonate- 0.42%

Bromide- 0.19%

Borate- 0.08%

Strontium- 0.04%

Fluoride- 0.003%

Other- less than 0.001%

As you can see, calcium is actually less than magnesium, so even the Wonder Shells that I promote are out of balance here. The Calcium in Wonder Shells is used as a carrier and will raise your GH, at least the other proportions (with the obvious exceptions of Chloride and Sodium) are in basic proportion to this other than the Calcium.

For more about Calcium, Electrolytes in aquariums, please read this article:

CALCIUM, KH, AND MAGNESIUM IN AQUARIUMS; How to maintain a Proper KH, why calcium and electrolytes are important.

RELATIONSHIP BETWEEN OCEAN WATER AND INTERNAL CHEMISTY OF ANIMALS:

I brought up ocean water chemical analysis to make a point that is the plasma and internal chemistry of all animals and fish is similar in composition to the ocean. This is why many electrolytes (elements) are important in the chemistry of aquarium environment (even fish food!)

Rene Quinton is a scientist who died in 1925.

"He postulated that from the mineral point of view, human and marine plasmas are environments of the same nature. In other words, there is physical and physiological identity between seawater and the internal environment of the organism. Not only do they exhibit very similar mineral compositions, but the particular form, organization and synergy of trace elements and mineral salts that make up the saline matrix of seawater closely resemble those of the internal environment constituents."

For more about proper Osmotic Function in fish, pleas see this article:

PROPER OSMOTIC FUNCTION

SUMMARY;

Basically my point is that all you add to your aquarium (freshwater or saltwater) should emulate this ocean ratio as close as possible, so why would you want to throw a product in your aquarium manufactured by heating gypsum?

For my full article, please visit this URL:

The Difference between Plaster of Paris and Aquarium Products such as Wonder Shells