Flourish comprehensive will solve this problem for the short term, but the Ludwigia won't completely change and grow the best it can since flourish comp. has macro nutrients (N, P, K) in very marginal amounts - not nearly enough to serve plants' needs. I recommend dry ferts for this --- "nilocg" on these forums is an excellent seller and source of help when it comes to ferts and dosing, maybe you want to try dry ferts (they're cheaper in the long run and will give you growth you wont believe is possible)hmm... thanks!
if i start dosing some ferts, should this go away? Should I go with Flourish?