ludwigia peruensis question
I've set up a 75 gallon with 4 2x32w ODNO lighting, DiY CO2, flourite gravel. Been running for 3 weeks, 2-3x weekly dosing NO3 and PO4 to keep levels 10 and 1. Heavily planted, with everything in it growing well except the ludwigia peruensis. The top leaves are nice and red, but the lower leaves are either falling off or are dark green. The main concern is that half of the stems are rotting mid-way, even though the tops of the stems seem to be doing well (healthing looking red leaves).
Is this a lighting issue, or is there anything else I can try to salvage these plants?