Holy crap that frogbit multiplied like crazy haha... I might have to make a little pen with straws to keep it in place or something. I wouldn't want it covering the light for the other plants.
Too bad about the OEBT. You can always try your hand at them later on! Or you can wait for tigers cause one of mine is berried
Did you boil the DW? I find that if I boil it, it sinks much faster. If you get some moss and cover the rocks and part of the DW you could potentially keep that as a permanent scape. It looks pretty mountain-like in that corner there!