Step 1: Remove water from farming ponds and settling ponds. Remove harmful creatures (shrimp, crabs, snails, insects, fish, etc.). Dredge pond; repair banks, water drains and supplies. Create a slope in the bottom of the pond toward the drains. Thoroughly compact the pond or use canvas to prevent erosion and limit leakage. Use net to fence around the pond to avoid intermediate host species from external environment such as crabs, sand bubbler crabs, snakes, etc.
Step 2: Apply agricultural lime dosage indicated in Table
|pH of the soil in pond and at the bottom of the pond||Lime (tons/ha)|
|4.5 to 5.0||2.5 - 1.5|
|5.1 to 6.0||1.5 - 1.0|
|6.1 to 6.5||1.0 - 0.5|
Step 3: Harrow thoroughly to soak lime into soil to eliminate shrimps, crabs, sand bubbler crabs, snails, insects, and fish left; kill bacteria in the mud; detoxify heavy metals, H2S and neutralize pH. Ponds with canvas in the bottom just need to be disinfected.
Step 4: Dry the pond in 20-30 days.
a. Placing the paddle wheels
1.5 m from the bank.
The distance between two paddle wheels is 60-80 cm; staggering the paddles.
Depending on the shape of the pond, arrange paddles appropriately to create a better flow and provide enough oxygen for the demand of shrimp.
b. The number of paddle wheels
|Pond area (m2)||Density: 15-20 prawns||Density: 20 - 25 prawns||The rate of rotation (cycles/min)|
|3.000||20 - 25 paddles||25 - 30 paddles||100 - 120|
|5.000||50 - 60 paddles||60 - 80 paddles||100 - 120|
Whiteleg shrimp has a large demand for oxygen. Therefore, it is depending on the stocking density to design aeration systems with paddle wheels, or a combination of plastic paddles wheels aerators with spiral aerators or other types of paddles to provide enough oxygen for shrimps in ponds. The rotation of the plastic paddles should be more than 120 cycles/min