Limnophila aquatica problems

Got one of these a couple of months ago. Looked stunning to start off with and then began to look, well, kinda stringy? It wasn't it's usual feathered, glorious self, but didn't seem to be dying either. Put out these odd looking green, leafy 'flowers' (that's the only way I can think to describe it). Still looked pretty good, but then the lower leaves started to die off. Now I just have those 'flowers' and hardly any leaves as they all died. The stalks and the 'flowers' seem fine but I can't seem to tempt the leaves to grow back.

It was originaly in a planted 60 litre with a 15W T8. Moved it to my 65 litre planted community which has CO2 and two 11W bulbs, but not improvement. Both tanks have fairly fine gravel and fertiliser tablets in the gravel, but no specialised substrate and no daily/weekly liquid ferts.

What am I doing wrong?

Oh, and I can't for the LIFE of me get cabomba to stay alive. It's supposed to be a really hardy plant, but while I can get almost anything else to grow it insists on going slimy, brown and generally dying. I've pulled it out and put it in a tub on the windowsil, and it seems to have stopped dying, but from the masses I had of it I now only have one decent sized bunch. Are the other plants out-competing it, or something? I regularly do plant maintainence and trim off lower leaves and anything brown/yellow/stringy, but it doesn't seem to have helped and I keep having to throw away entire stems.

The aquatica can have its tops cut off and the stem replanted, this should generate the display again. The fluffy bits come from the flower so to speak.
Try growing the Cabomba in a shaded area of the tank. I find too much light and eventually it goes weird.