Im considering building my own but will be using Seachem Matrix instead of Calcium Carbonate because the way a sulphur denitrator works is by anaerobic bacteria that feeds of sulphur. Seachem Matrix is a good media to host the bacteria so I might use 1/3 sulphur and 2/3 Seachem Matrix. The Matrix is larger in size than the Seachem Denitrate thus less clogging in the long run. Ill run the Calcium Carbonate in a 2nd reactor. Here is a great site that explains how to maintain a denitrator correctly
http://www.njreefers.org/joomla/inde...&topic=4537.15