The talk about spacecraft life support systems linked below (https://media.ccc.de/v/rc3-158638-how_to_survive_in_spacecra...) gives a thorough overview over the possibilities for plant-based oxygen generation.
of course there are lots of factors, especially with illumination/surface area
Also, fresh spirulina is most comparable to tofu. Very little flavor, gag-worthy sponge-like texture. Was trying to make fish feed but had to eat most of it myself as the fish and the dog wouldn’t touch it.
Shut down the operation after a few harvests. Mine was kept warm by sitting on top of a water reservoir that water cooled other grow lights for my main indoor garden, but keeping it warm would be the major cost in most climates, as it grows best in 90 deg F water.
Nevertheless, fully optimized 17l of algae do seem believable, if well cared for.
¹ ignoring diet levels and differing CO₂ / H₂O ratio for fat vs. carbs etc.
² no idea how efficient algae are, but wikipedia says they are very efficient