Hey I think you are off to a great start. I have a Fluval Spec V but only have java fern, java moss, flame moss, and H. polysperma. Everything has been fine with stock lighting no real growth besides on the H. polysperma but that is pretty much expected. I think for now you should try it out and see how it treats you without adding anything. I think you might be able to keep DHG alive with the light but the growth might be super slow. It is kinda trial and error, some people have great luck with the stock light while some don't. Either way keep us posted on what you end up doing!