"Blackwater" plants

I have no idea which sub to post this in, it could fir in most. I am starting up a South American, blackwater type aquarium. Not a pure biotype, just something in that general vein. softish water, pH 6.6-6.8, etc. The main inhabitant of this aquarium will be a black ghost knife. Anything that won't work with that will be scrapped, lol. I am a relatively experienced hobbyist, with fish anyways. Until the last week of setting up this tank, I could count the number of times I've tested kH, gH etc, on one hand. I need to understand what plants will work in this setup (also keep in mind, I've never tried a planted aquarium).

The current dKh is 3-3.5 (slight change after 3 drops on the API test kit, completely after 4), the dGh is 13 (13 drops on the API). The pH is 6.9-7.0. Keep in mind this tank is still cycling (well, but the tank is only 6 days old.) I posted most of the other particulars in my intro thread (http://www.plantedtank.net/forums/1...anks-site-actual-aquaria-lol.html#post9840330), but any other questions please ask. Currently I have a ZooMed Flora Sun (5K I think) T8 fluorescent on the tank.

I want to figure out what all else I need to do to get the planted part of this system stable before getting the knife. What plants are good, lighting, etc. I'd like to add some type of "lily" type plant (dwarf lily, lotus, banana, etc) to the tank as well). But I need to balance the plants underneath that (as well as the large sword I already have with floating leaves) with the appropriate lighting and water conditions. I mean, I understand things in theory, but I have no experience in practice. It's a 20" deep tank, with a filter rated @ 300 GPH, so filled with media lets say 200 GPH. If the tank is sufficiently plated will the fish get enough oxygen without an aerator to create surface disturbance? I have the tank filled to where the flow of the filter is not "falling", but creates great circulation in a counter clockwise motion. I'd prefer to keep this, but I need to get sufficient oxygen to the fish. Which requires healthy plants methinks.