5g tanks is a high tech tank with CO2, more fert. 20G tank is low tech tank, no Co2, low fert. There are a lot of pearling on my rotala in the 5G tank, none in the 20G tank. Most of the pearling appear on the tall stems which almost reach the surface, and those have more crease lines. While the low stems without pearling have no crease lines. Is the pearling effect making the damage, but that does not make sense.