Tanks can be kept up and running without filtration provided you have lots of plants, an air pump to agitate the surface of the water, and you keep your tank understocked.
(Tanks; can be kept up; ) (you; keep; your tank) (Tanks; running; ) (filtration; provided; ) (you; have; lots of plants) (an air pump; to agitate; the surface of the water)
Tanks you Tanks filtration you an air pump
can be kept up keep running provided have to agitate
your tank
lots of plants
the surface of the water