A closed photo-
bioreactor, which in at least one example comprises a plurality of flexible, repeating, substantially enclosed, parallel chambers flexibly connected along their lengths, where a liquid growth media is substantially still without the need for turbulent mixing of the bulk liquid. In many examples, each is connected into integrated, flexible pipelines that serve to supply gas to the chambers, to vent gas from the chambers, and to fill and drain the individual photo-
bioreactor chambers of their liquid contents. In some installations, a
bioreactor will be rolled up using, for example, a long rod as a spool, for storage and transportation. Some examples will be manually unfurled and positioned on an angled site including, for example, an earthen
berm. In many embodiments, a photo-bioreactor will be manufactured from thin plastics using low cost manufacturing techniques. In at least one example, a photo bioreactor is described in which bubbles with a substantially non-convex shape are introduced to mix the liquid contents.