I talked to my LFS guy. I told him that the new plant growth wasn't
as thick as the old plant that I bought. He said that the Egeria
densa that I bought was grown in Florida, outside, in very nutrient
rich water. It also grows in very dense groups, meaning that the
individual stems are very close together. They are then harvested by
cutting off the tops of the plant.

These plants receive natural light, probably in shallow water. I'm
not sure how exactly I can re-create that. These plants may have been
growing slowly considering it is now March and these plants were
probably harvested some time around February. In outdoor conditions
that would mean that light was not at its peak and the plants probably
grew slower and more dense. In addition the water temp was probably
at its lowest for the year, also meaning slow growth. Finally, the
water that they grew in was probably a lot more nutrient rich than my
water. I can probably increase some of the nutrients in my tank, but
probably not to the level that they orginally grew in. From what I
was told, the environment like a muddy river. I could probably just
drop some laterite in my tank to make it look like that, but it still
wouldn't be the same. This might also mean that the plants are only
getting light from the top. This could make their leaves fuller.

One of the few things that I am going to try it to grow the plants
very tightly packed. I have been replanting the new growth within the
same area. Hopefully this will cause the plant to try and grow fuller
and not just taller. It doesn't seem to make sense, but it is worth a
shot.

I've been considering doing an experiment in a bucket in the basement
where it is cooler and I can control the light more. I was thinking
that I might make the water super rich, and do the same for the
substrate. My basement is much cooler right now and then I can change
the amount of lighting to see if it makes a difference. If that
doesn't work, I can change the temp. We'll have to see about that
experiment, no promises.

Let me know if you draw different conclusions that I did.

As I side note, my Echinodorus cordifolius that is growing next to the
Egeria densa does not have any black or brown algae growing on the new
leaves. The Egeria densa seems to be pulling a lot of the nitrates
out of the tank, which is what I wanted with my goldfish. I had
nitrates over 40 ppm and now it is down to 10-20 ppm.