Lilaeopsis observations, and a phosphate removal media question

I have some observations about a Lilaeopsis species plant I picked up
lately. I have this stuff growing in a 10G tank in my office, with two 13W
compact fluorescent fixtures, and 1/2" of 50% earthworm castings under 3
inches or so of .65mm silica sand as substrate. This is a little too small
of a grain size - next time I will make the effort to find larger sand. The
tank has yeast CO2 injected into a small powerhead, and trace element
fertilization with Dupla 24. Temperature is at 74 to 78 Fahrenheit, KH at
about 3dKH. pH runs between 6.7-7.0.

BTW, in small tanks like this, pay very careful attention to fertilization
amounts. I overdosed with KNO3 about a month ago and am still fighting
unicellular algae.

The plant, definitely Lilaeopsis, was labeled as Lilaeopsis
novea-zelandiae. I thought this would be perfect for such a small tank,
since that species does not grow very tall. I soon learned that it was
mislabeled, or that this species grows differently in my aquarium, as some
specimens in my tank are now about 8 inches tall, or over twice as tall as
the literature suggests. This stuff (can anyone suggest what species it
might be?) went absolutely nuts in this aquarium. From one clump a few
months ago, it has now propagated to take over nearly all the available
surface space. In fact it is almost choking out plantings of Sagittaria
(subulata, I think) and Echinodorus tenellus. Before I started fertilizing
with trace elements, I think the Lilaeopsis was outcompeting even those
fast-growing plants for nutrients, as their growth was very limited for a
while and I saw symptoms of nutrient deficiencies. But it is possible they
were simply taking a while to become acclimated to higher light levels and
so on. Since they have become established the other plants have also done
well, sending leaves all the way up to the water surface. It is possible
they are growing taller than they would otherwise, due to the intense
competition for light the Lilaeopsis provides closer to the substrate.

The reference materials I have (Baensch vol. 2, James, Rataj/Horeman)
unanimously say this plant does well in very bright light and rich
substrate. My substrate qualifies as rich, but the lighting isn't all that
bright, although it is brighter than the watts per gallon figure (2.6)
would indicate, as the water is shallow. So if you want to keep this stuff
in your aquarium, you would definitely be able to get away with lower light
figures than the literature suggests, especially if you don't need or want
explosive growth.

On another topic: Have list members used and/or had good experiences with
phosphate-removal filter media? I am pondering getting the phosphate
concentration of the water in another tank down as close as I can to zero
as a tactic in the Great Fibrous Algae Wars. This tank has a Fluval
canister filter, which has a yawningly empty center space, and it calls to
me in the night saying "fill me with PhosGuard" and the like. The only
downside I can see to these filter media is that they would get very
expensive if you used them on a regular basis, primarily because (according
to the labels on the packaging, anyway) they lose efficacy quickly. Do
these products put any unwanted ions or chemicals into the tank water? Do
they remove critical trace nutrients like activated carbon would? If not,
they sound perfect for a month-or-two application so the vascular plants
can starve out the algae.

In grey, sprinkly Seattle,