I've been growing plants in normal gravel, and they seem to be doing pretty well. I'm going to experiment with playsand in a 10 and see if I get any difference. I do end up using root tabs for my heavy root feeders though. To a certain extent it depends on what you want to grow. Amazon fern, and most plants that can be floated really won't worry too much about your substrate. Things like Amazon sword, sag, etc. that are really root feeders will probably do better with one of the plant substrates.