#ed_op#DIV#ed_cl#Hi all,#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#I'm about to set up my new 120g tank and after experience with the current 50g tank, I want to build a system that will support high stock level of fish, some coral and lower nitrate level. (currently, the 50g does a good job of getting rid of ammonia and nitrite but cannot get the nitrates low enough).#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#Question 1 - I am planning on having a sand bed on the display tank of 3 inches of No. 1 grade (fine) coral sand. Is that deep enough to get anerobic nitrate-eating bacteria ? Due to the design of the overflow, I cannot go higher than 3 inches.#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#Question 2 - Does it help to put some sintered glass rings at the bottom of the sand bed to increase the surface area for those bacteria ? Does it work or will it fail - it will be in fine coral sand.#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#I will have a small refugium in the sump - if the answer to Q2 above is yes, it works, I would put more sintered glass rings at the bottom of that one - I plan to have about 4 or 5 inches of fine sand in the refugium.#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#Any opinions ?#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#Thanks#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#shlim944#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl#