How to calculate the amount of chemical to be used in Fish ponds
You may wish to make a stock solution, a working solution or a treatment dosage of the chemical concerned.
The concentration required will be determined by the type of chemical and treatment used and the amounts used will depend on the concentration and the overall volume of the container, tank or pond involved.
Calculations of the amount to be used depend on the way the dosage is expressed and on the percentage of Al present in the chemicals.
If you are using a chemical with 100 percent Al, proceed in one of the following ways.
(a) When the concentration is given as a weight or volume of Al per volume of solution, multiply this concentration by the total volume of water to be treated.
A concentration of 3 mg/l malachite green is required as a treatment dosage. Your tank contains 2 m3 = 2000 litres
You will need 3 mg/l x 2000 l = 6000 mg = 6 g malachite green. A stock solution of 1 g/I copper sulphate is to be made, to use in a 5-l drum. You will need 1 g/I x 5 l = 5 g of copper sulphate.
(b) When the concentration is given as a percentage, multiply this concentration (expressed as a decimal number) by 1000 times the water volume (in l) to obtain the amount of chemical in ml or g.
Recommended treatment dosage is 2 percent common salt. Your plastic barrel contains 30 l water; you will need 0.02 x 1000 x 30 l = 600 g salt.
(c) When the concentration is given in parts per million (ppm), multiply this concentration by the water volume (in l). Divide the result by 1000 to obtain the amount of chemical in ml or g.
Recommended dosage is 100 ppm copper sulphate. Your trough contains 500 l water. You will need (100 ppm x 500 l) � 1000 = 50 g copper sulphate.
(d) When the concentration is given as a ratio, multiply this concentration by 1000 times the water volume (in l) to obtain the amount of chemical in ml or g.
Recommended concentration is 1: 6000 formalin; your tank contains 2000 l water; you will need (1 � 6000) x 1000 x 2000 l = about 333 ml of formalin.
If you are using a chemical that contains less than 100 percent active ingredient, divide the result obtained from the above calculations by the percentage of Al (expressed as a decimal) in the chemical.
Recommended dosage of an insecticide containing 80 percent Al is 0.5 ppm Al. Your pond contains 50 m3 = 50000 l water: calculate amount of Al required as (0.5 ppm x 50000 l) � 1000 = 25 g;
calculate amount of chemical required to provide this as 25 g � 0.80 = 31.25 g.
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