Every hydroponic grower, large or small, has to choose between buying fertilisers and trace elements and mixing his own solutions or buying ready mixed nutrient blends. The blend might be formulated according to the growers specification with due regard to his raw water quality and crop needs, or it might be a manufacturers standard blend for a particular crop and average water quality. Some blend manufacturers provide a complete breakdown of the nutrient content of their blends, other prefer to keep these important details secret. Some blends fall into the class of magic nutrients with added extra vitamins, growth promoters or chemical elements not known to be essential for plant growth but according to their makers having magic effects on growth and yield.
The best crops will result from nutrient solutions that are well matched to the uptake demands of the crop being grown, and any blend that is to be purchased should be specified according to the needs of the crop and the water supply. When this is done the recirculating nutrient solution will continue to provide the correct balance of nutrients to the crop over a long period of time. Using blends that are not so well balanced against the crop requirements will result in result in the accumulation of some nutrients in the recirculating nutrient solution to well above optimum concentrations and the depletion of other nutrients to well below optimum concentrations.
Obviously the knowledgeable grower who makes a properly balanced nutrient solution will obtain the best crops with the most efficient use fertilisers and probably the lowest nutrient cost. A supplier making blends to the growers specification might be able to do so at a lower cost through bulk buying of larger quantities of fertilisers. The efficiency and cost of standard and magic blends will usually be considerably higher than the cost of a grower making his own mix.
The bottom line is that solutions properly made by growers will produce heavier crops of better quality at a lower cost than nearly all commercially available blends and the reason why all growers should learn how to make their own mixes is the improvement in the profit from their business.