NOVELTY - Process-I for the enhanced production of one or more metabolites in microalgae and/or cyanobacteria, comprises: (i) culturing a microalgal or cyanobacterial strain through a production phase; and (ii) exposing the microalgal or cyanobacterial culture to a stimulus, where the stimulus comprises (a) a decrease in pH to a pH of no more than 6, followed by an increase in pH to a pH of no less than 7 and (b) an increase in light irradiance to at least 400 mu mole/m2/second.    USE - The processes are useful for: the enhanced production of microalgae belonging to the family Pleurochloridaceae containing commercially valuable bio proteins, lipids and metabolites of eicosapentaenoic acid, myristic acid, palmitic acid behenic acid, laurie acid, linoleic acid, alpha linolenic acid and stearic acid; the enhanced production of carbohydrates including exopolysaccharide; and the enhanced production of algal and/or cyanobacterial biomass, where the algal and/or cyanobacterial biomass is useful for the production of biofuel, and as a soil conditioner or biofertilizer (all claimed). No biological data given.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) a process-II for the production or growth of microalgae and/or cyanobacteria or the production of one or more metabolites derived from it, comprising (ia) an adaptation stage of culturing microalgae or cyanobacteria (a1) on a process water feedstock and selection of those microalgae or cyanobacteria able to grow on the process water feedstock, and/or (b1) under LEDs emitting 2 peaks of red and blue light within the spectrum of light wavelengths of 400-700 nm, and (iia) a production phase of culturing the selected microalgae or cyanobacteria of (a2) on the same process water feedstock used in the adaptation stage and/or under the same light conditions used in the adaption stage; (2) a microorganism-I which is, or has the identifying characteristics of, a strain of Chlorogibba allorgei deposited with the Culture Collection of Algae and Protozoa under the accession number CCAP 817/1, or a mutant strain derived from it; (3) a microorganism-II which is, or has the identifying characteristics of, a strain of Dictyosphaerium chlorelloides deposited with the Culture Collection of Algae and Protozoa under the accession number CCAP 222/98, or a mutant strain derived from it; (4) a process-III for the enhanced production of microalgae belonging to the family Pleurochloridaceae containing commercially valuable bio proteins, lipids and metabolites of eicosapentaenoic acid, myristic acid, palmitic acid, behenic acid, laurie acid, linoleic acid, alpha linolenic acid and stearic acid comprising using optimized light wavelengths for the culturing and production preferably in photobioreactors of lipid-rich micro-algae strains within the phylum of Chlorophyta and the family of Pleurochloridaceae; (5) a process-IV for the production of fatty acids such as eicosapentaenoic acid, myristic acid, palmitic acid, behenic acid, laurie acid, linoleic acid, alpha linolenic acid and stearic acid comprising preparing the algae biomass belonging to the Pleurochloridaceae family and the cyanobacteria strain from the order Chroococcales in the genera Synechocystis and Synechococcus and isolating the commercially valuable by products from the lipid(s); (6) a process-V for obtaining production of specific fatty acids in the lipid profile comprising tuning photosynthetic efficiency in the presence of select continuous light PAR wavelengths; (7) a process-VI for obtaining specific production of fatty acids in the lipid profile comprising adjusting nutrient levels in growth media with light irradiances to provide products/ingredients for either the food or cosmetics sector or for the production of biofuels; (8) a process-VII for improving the growth profile of algal cells and/or for altering or controlling the metabolite production profile, such as the fatty acid profile, of the algal cells comprising adapting the algal cells to specific conditions through multiple rounds of sub-culture with exposure to the specific conditions prior to recovery of metabolites from the algal cells; (9) a process-VIII for double phase continuous production of exopolysaccharide by cultivation of a micro-alga in an aqueous nutrient amended culture in the presence of dissolved carbon dioxide and tuned incident light energy supplied by LEDs, where exopolysaccharide production is enhanced by causing the culture to shift from a growth phase favoring cell division to a static phase favoring exopolysaccharide production, comprising (ib) carrying out the growth phase in a first stage operated in a continuous mode in which fresh nutrient medium or secondary process water supply is used to grow the culture to sustain exponential cell growth, and (iib) along with the supply of fresh nutrient medium and carbon dioxide to the first stage, transferring a portion of the culture to a second stage which is separate from the first stage and in which the supply of carbon dioxide and nutrients is limited to create the conditions in the second stage to enhance exopolysaccharide production while continuing to supply tuned photosynthetically active radiation (PAR) Light at set irradiance levels from tuned LEDs, whilst optionally, fresh nutrient medium or process water is also added to the first stage to continue the growth phase, optionally simultaneously; (10) a soil conditioner comprising algal biomass produced by the method-VIII; (11) a subsurface dip irrigation system comprising the soil conditioner; and (12) a system for the production of algal exopolysaccharide, comprising a first stage reaction chamber adapted to contain a culture of algae cells and having an inlet for the introduction of a nutrient medium and carbon dioxide to the chamber and an outlet for the withdrawal of culture from it, means for sensing the cell density in the chamber and generating a control function representative, means responsive to the control function for regulating the introduction of nutrient medium and carbon dioxide to the inlet and the withdrawal of culture from the outlet, second stage reaction chambers adapted to receive culture from the first stage reaction chamber, and a means for sequentially transferring culture from the outlet of the first stage reaction chamber to the second stage reaction chambers.