Who Gives A Fish Forums

For real, my Ludwigia did the same thing till I switched to a stronger light. Now it's bushy as heck. You could also try trimming the tops and replanting, that'll force bushier growth down low. Just don't go hacking more than a third at once.

Yep, sounds like a light issue to me. That Finnex is decent but might not be cutting it for stems if they're reaching. You could try lowering the light a bit or adding a second one. What kinda stems are we talking? Some are way more demanding than others.

I think using carbon might help with the foam issue. It's worth a shot, at least.