Who needs a lava lamp when you've got a tank full of Duckweed! At first, when I noticed we had a few of these tiny plants floating in our tank, I was cautioned against leaving them in there for fear they would rapidly overrun our 125 gallon fresh water fish tank. The problem being that they could soon reach such vast numbers that their presence would inhibit the light reaching the plants living below. I am, however, taking increasingly more and more delight in watching the way they move as they get caught in the ebb and flow of the miniature currents of our tank. They slowly spiral toward where either of the two water return spouts spill into the top of the tank, occasionally getting pulled under as the rushing water proves to be too much. Down they plummet through the water column. Gradually they situate themselves upright and delicately drift back up to the surface. This produces a continual random stream of periodic floaters. A few of the unfortunate souls become lodged beneath one of the broad leafed plants. Perhaps a fish will cruise by close enough to disturb the foliage and set the captives free, or maybe a fiddler crab will be their savior as he jostles the vegetation trying to reach new heights. So, no, I will not so hastily eliminate our Duckweed population. I will, however, be inclined to cull the masses from time to time.