Excellent explanation, FF.
Just to add a little personal experience to this - before our current tank, we had a 75g with a CC
bed. I could *never* get the nitrates in this tank below 20-30ppm. Interestingly enough, it was a thriving softy/shroom tank which exhibited *tons* of growth. I would *never* chance this if I were attempting to do sps
- which is the main reason we changed to a DSB
with the 180g.
However, I honestly believe that some softies do better with some level of nutrients in the water - they don't need the absolute pristine conditions that sps
require. I am by no means promoting the use of CC
as a substrate - a DSB
is simply a far superior substrate for a reef tank, for denitrification amongst other reasons. I simply wanted to mention that some softies/shrooms
, etc. can do well in less-than-perfect nitrate levels.
A side note - you mentioned "adding" LS
. As FF mentioned, CC
substrate by nature usually maintains a somewhat elevated nitrate level (due to the grain size/trapping detritus). Adding LS
will not solve this problem - you would need to remove the CC
and replace it with LS