Plant ID? WT-HECK

[tabman2]

This thing is about 3 inches wide now and 3 high.. it seriously grows more everyday.. I didn't care so much when I could barley notice it ... but holy smokes..

 

[natan]

looks like kelp 2 me.

 

[piercho]

Its probably Sargassum. Sargassum is a brown algae that tends to grow up from a single holdfast. As it gets larger you may see the development of 1/8" diameter (approximately) balls at the terminal ends of the fronds. These are hollow and provide bouyancy to the plant. I've had Sargassum growing from the bottom to the water's surface of a 26" deep tank. Easy to harvest and not likely to become invasive.