1. (isolation) If the algae source is freshwater, I recommend first isolate few targeting species from the collection samples using agar-nutrient plating techniques, nutrients would be BB (Bold Basal) medium.
2. (Culturing) Then make the BB medium again, then autoclave, then poured it to transparent and graded plastic or glass bottles (60% filled by nutrient). Then mix minute portions of the isolated sample to the bottle with nutrient solution.
3. Keep the bottle in controlled growth room
4. Shaking the bottle two times daily. Hopefully it will works.