Metronidazole and plants

There is a thread on the Discus-List at the moment discussing how in some 
cases a treatment with Metronidazole has, as a side effect,  increased the 
growth of plants and algae. Would any of you have any knowledge or care to 
comment on this topic? I am not suggesting that  Metronidazole be used as a 
plant supplement but I would be interested to know how it may be working.

Those who have described this effect have mentioned that leaf colour goes 
from light green / yellow to a bright green. So perhaps the metronidazole is 
acting as a chelating agent for Fe or some other trace element. I may be 
wrong but I get the feeling that they are talking about plants that are 
growing under unfavourable conditions, so this effect may not be apparant in 
a tank full of healthy growing plants.