i haven't had any troubles with my moon sand. I used it with my eco complete, makes planting easier, no compaction problems, and plants growing like crazy (not because of the sand of course, but they stay down in the eco better!) Not sure how well it will look mixed with the flourite. As long as you rustle up the substrate every week or so where you can while doing water changes, you shouldn't have any horrible problems. It is a very fine grain though, and likes to get into impellers and things like that. I wish there was a thicker grain sand in black that I could find around here because I would have preferred that over the TMS, but I haven't had any problems as far as growing plants, compaction etc.