How to calculate the dosage of reverse osmosis scale inhibitor?

Reverse osmosis antiscalant dosage is a must to master, because once more or less will affect the inhibitor effect of the use of reverse osmosis, so how to calculate the reverse osmosis antiscalant dosage?
Reverse osmosis scale inhibitors greatly delay the fouling of reverse osmosis membranes and prolong the service life of reverse osmosis membranes, which is the important reason why reverse osmosis membranes need to be added.
The recommended concentration of reverse osmosis scale inhibitor is 3-8ppm, that is to say, reverse osmosis equipment needs 1 3-8g of water per inlet.
Formula of monthly dosage: W=Q * S * H * 30/1000, where W is the monthly amount (Kg); Q water flow reverse osmosis equipment (m3/h); S dosage (3-8ppm, g/, H tons) for reverse osmosis equipment working time (hour); 1000 for conversion the amount of G and Kg, if a reverse osmosis water production is 75 tons / hour, the water is at least 100 tons / hour, month dosage: 100 x 3.5 x 24 x 30/1000=252KG2.