Water Wisteria Stem Turning Brown

[508]

Hi,
 
I have recently added about 8 or 7 stems of Hygrophilia Difformis to my tank, commonly known as water wisteria.
 
The leaves and stem above the surface are doing okay, however when one of the stems sometimes floats out of the substrate one of the bottom bits are brown and seem to be rotting. The smell especially of that particular brown stem is horrible. Any ideas on why this is happening?

 

[Byron]

Are roots sprouting from the buried portions of the stems?
 
Byron.

 

[508]

Doesn't seem so. The stems seem to be rotting though I haven't checked some of them. The ones that will go up to float will have rotten portions of the stem

 

[Byron]

Doesn't seem so. The stems seem to be rotting though I haven't checked some of them. The ones that will go up to float will have rotten portions of the stem

 
Try cutting off the brown portion of the stem of a couple stalks, so you have just healthy stem and leaves, and leave them floating, not rooted.  I was about to ask for data, when I remembered our previous threads, so I've checked those.  We had some light issues and lacking specifics for the "pink" tube.  This plant needs strong light, and being fast growing, good nutrients to balance.  Will this fixture take basic T5 HO tubes, or do they have to be specific from the manufacturer?  Did you by any chance use one of those Osmocote tabs next to the rotting stems?