Better than that.. the tank will get some air from teh atmosphere and needs to, as plants at night need o2 also. but if you use a lot of plants.. medium light.. and some co2 .. (you can do it yourself with yeast, a soda bottle and tubing) then you will be able to get what is known as pearling... which is o2 bubbles rising from the plants themselves and sitting on the leaves.
the complication here is that you need to cycle the tank before you add any fish.. so if you want fish in the tank too, you will need to wait several weeks to put them in.. but plants can go in right away.
go over to the planted tank forum and start asking questions about the simplest set up you can manage that will induce pearling.. a true low light tank, won't.. but then again that brings to mind a different experiment.. the difference between a tank that grows algae and one that doesn't. I have a low light tank where i keep three dwarf african frogs. The tank doesn't have a speck of algae, because even though I don't have enough photosynthesis going on to cause pearling, the plants use up all of the "nutrients" ie waste, that the algae would live on.. and essentially starve the algae out..
YOu can show how higher life forms take over from the single celled organisms simply by having an algae free tank... this way you don't have to invest in co2 or even high light.. I have a cheap 2.5 gallon tank that came wiht a little internal filter and an 8 watt bulb.. I filled it full of anubias and moss, and a little bit of other cuttings to see what will live and three months later, no algae!!!
Easier experiment, cheaper to run, and really shows a lot about how ecosystems mature...
go on over to the planted tank forum and learn ;0 )
