er is a post from another thread realted to a common start up issue. Nitrates don't go down for a long time in some tanks:
I would stay the course and go slowly even though you may have room to go up some. FWIW, I'm settled in at 40vodka equivalents for 650 gallons.
Many don't see nitrate reduction for many months.
I think it took Melev a noted reefer here on RC in the past over 8 mos for nitrates to drop even though PO4 in his tanks dropped soon after dosing started.
In my case ,I used a diy sulfur dentrator to take down the nitrates from the 50 to 80 ppm range in a 650 gallon system in matter of several weeks to near zero. That was over 5 years ago. Since then even with heavy feeding they have remained very low. They hovered around 5ppm for several months though and then just dropped to undetectable.
One study I read notes heterotrophic bacteria (like those encouraged by carbon dosing) take N from ammonia directly to microbial mass. This would cut down on the production of nitrate through the usual autotrophic bacterial route via ammonia oxidation but wouldn't do very much to remove nitrate that's there already .A different pathway via the removal oxygen from nitrate,ie, the usual aerobic activity would .
So, it seems high nitrate might take a long time via the normal anaerobic process to deplete and carbon dosing likely won't make it faster in a direct way if the heterotrophs take N form ammonia directly ; the extra heterotrophic bacterial activity would just cut down the new nitrate supply.
This scenario may explain why folks who start carbon dosing with relatively low nitrate levels ( say less than 5ppm ) can keep them there and after a period of time se them fall further. While , those who use soluble organics to drop existing high nitrate levels often find it takes an inordinately long period of time .
Unfortunately , some push it and wind up with the nasty consequences of overdosing which in some case are quite significant including fish and other animal killing oxygen depletion from blooms, stingy messes throughout the aquarium and a buildup of unused total organiccarbon.
Here is the study fyi:
http://ag.arizona.edu/azaqua/ista/IS...%20Ebeling.pdf
This is from it:
The three nitrogen conversion pathways traditionally used for the removal of ammonia-nitrogen in
marine shrimp aquaculture systems are throug
h the conversion of
ammonia-nitrogen via
photoautotrophic algae directly to algal biomass, autotrophic bacterial to nitrate nitrogen, and
heterotrophic bacterial directly to microbial biomass.
