i have decided to switch substrate from gravel to T-grade color quartz. i have done a couple of days worth of research on t- grade color quartz and it took me another couple of days to finally find a person that know what i was talking about and that had some in stock and was willing to sell to me at 40 dollar for a 50 pound bag a little steeper then i thought. so what my question is has anybody used and do you guys like it? Also how much of it does it tank to fill a 55 galloon tank.