About calcium supplementation in aquaculture

1. About "calcium"
Nowadays, shrimp and crab farming are becoming more and more popular, and calcium supplementation is an indispensable part. The calcium content in the water body not only affects the doubling rate of shrimp and crabs, but also affects various important components in the aquaculture water body. Calcium is an important component of bones, scales, and carapaces of aquaculture species. In the case of calcium deficiency, aquaculture species will have delayed moulting time, slow down the speed of hard shells, and die. Calcium is also an important component of plant cell walls. In the absence of calcium, the speed of algae reproduction will be limited, and it will be difficult to fertilize and water, and the water color will easily become clear. In addition, it also participates in the restoration and regulation of the breeding environment. Crustaceans need to supplement a large amount of calcium before and after moulting to harden the carapace and promote their own growth.

2. Calcium supplement products on the
market At present, the main components of calcium supplement products on the market are: ①Organic calcium:calcium lactate, calcium gluconate,calcium citrate, etc.; ②Inorganic calcium:calcium carbonate, calcium oxide, calcium chloride, calcium phosphate etc.
Organic calcium absorbs well, but the calcium content is low and the price is high, so it is usually not added or rarely added; organic calcium raw materials such as calcium lactate are expensive, and in fact, most of them are inorganic calcium that is low in cost and can be absorbed by crabs. Inorganic calcium includes calcium carbonate (shell powder with a calcium carbonate content of 95%), calcium oxide (quicklime), calcium chloride, and calcium dihydrogen phosphate (slightly soluble in water, and the water body is acidic).
Calcium supplement products are generally made of these raw materials plus some auxiliary materials, some are made into water, and some are made into granules! Our "quick calcium supplement plus phosphorus" is inorganic calcium + organic calcium, and the organic calcium is calcium lactate.
In order for calcium to be absorbed by shrimps and crabs, it must first be soluble in water.
Calcium chloride has the best water solubility among inorganic calcium, relatively higher price, and unstable; calcium oxide and calcium carbonate basically belong to the same property after being put into water, and are difficult to dissolve in water; better calcium supplements on the market The product is called ionized calcium; ionized calcium is nothing more than calcium existing in water in the form of ions, and those that can be dissolved in water can call themselves ionized calcium. Another disadvantage of inorganic calcium is its slow absorption.
The effect of organic calcium comes and goes quickly, while inorganic calcium is relatively long-lasting, so calcium supplementation for shrimp and crabs requires both at the same time; in addition, calcium supplementation requires magnesium, phosphorus, potassium and other elements to be supplemented at the same time.  
Magnesium, phosphorus, and potassium are the main factors of animal ATP (adenosine triphosphate, which releases energy when hydrolyzed, the most direct energy source in organisms) synthase. When shelling shrimp and crabs, in addition to the need to regenerate the carapace, it also consumes a lot of energy. If only calcium is supplemented, but magnesium, phosphorus, and potassium are not supplemented, there will be weakness in shelling.
Magnesium, phosphorus, and potassium are also essential elements for plants in the water body. In addition to calcium, shrimp and crabs also absorb a large amount of these elements in the water body before and after shelling.
If these elements in the water body are insufficient, on the one hand, shrimp and crabs will be unable to shell, and on the other hand, it will also cause water material circulation obstacles, slow growth of aquatic plants, or a decrease in the number of algae.
Phosphorus and potassium are usually added when fertilizing water, but magnesium is rarely involved, so magnesium must be supplemented while calcium is supplemented.

A good calcium supplement product, on the one hand, should have good water solubility and have both organic and inorganic calcium; on the other hand, it should also supplement magnesium, potassium, phosphorus, etc., especially magnesium.
Quick calcium supplement plus phosphorus = organic calcium + inorganic calcium + magnesium + potassium + phosphorus