actually silica would be much less reccommended, it does work and much better than cc(IMO), but it is less safe tehn southdown in a reef tank
ps, we used only sd in our 2 tanks at work and guess what, they are happy thriving tanks(almost 5 months now), and my one lfs wonders why i never buy fish, unless we get a new tank, between our 2 we had at home and the 2 at work, we stock for a couple of months, and then we are done until we get a new tank, he ahs no concept of the idea you can keep a fish for 5 months, or in the case of our one tank, 16 or 17 months and counting
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)