Nitrate reducing tanks!

[blasterman]

I had a 20gal long packed full of large and rapidly growing paly colonies that would go from 15ppm nitrate to less than a trace in about two weeks. If I flipped my skimmer on the time cut in half. The amount of nitrogen fixation by soft corals is rather amazing. The problem is that if I didn't keep those levels high corals suffered. SPS handled the nutrient roller coaster better than many softies.

Algae, and this includes symbiotic xooenthalae in corals can consume ammonia if its present, but I was under the impression the process was metabolic limited. More ammonia wont make hard corals grow faster. They just consume it because it's less of work to metabolize than nitrate. Remember that nitrate and ammonia exist in trivial amounts in the ocean. The higher levels of these substances in our tanks is not a normal environment.

 

[Dan_P]

I had a 20gal long packed full of large and rapidly growing paly colonies that would go from 15ppm nitrate to less than a trace in about two weeks. If I flipped my skimmer on the time cut in half. The amount of nitrogen fixation by soft corals is rather amazing. The problem is that if I didn't keep those levels high corals suffered. SPS handled the nutrient roller coaster better than many softies.

Algae, and this includes symbiotic xooenthalae in corals can consume ammonia if its present, but I was under the impression the process was metabolic limited. More ammonia wont make hard corals grow faster. They just consume it because it's less of work to metabolize than nitrate. Remember that nitrate and ammonia exist in trivial amounts in the ocean. The higher levels of these substances in our tanks is not a normal environment.

How were you keeping the nitrates elevated?

 

[piranhaman00]

I use seachem matrix in all my tanks and I absolutely love it. I credit it to all my tanks using NO3 at a steady rate, but I’m also lightly stocked. In any case I use about 2-5ppm NO3 a week. I dose KNO3 weekly/biweekly during water testing to keep at around 10ppm.

 

[Belgian Anthias]

Most organisms inhibit nitrate uptake if ammonia is available as it is a waste of energy. A lot of photo-autotrophs are able to manage their nitrogen uptake following the ammonia/nitrate ratio, they have an unlimited energy source. This within their own microenvironment which may differ completely of what will be measured in the water column. It is all about nutrient availability, activity intensity, possible growth rates, and water exchange rates. Most denitrification takes place in a very active nitrifying biofilm! +- 16% of the ammonia-nitrogen entering a nitrifying biofilm may leave the film as N2. If the nitrifying biofilm grows on a substrate of elemental sulfur this may be a lot higher ( BADES rolls till +80%) Without nitrification of ammonia, this denitrification capacity is lost.
Fast growth is limited by the nitrogen source used and the availability of usable organic carbon. For example, if carbohydrates are added very fast heterotrophic growth may be induced as long ammonium is available, using up most ammonia because autotrophs will not be able to compete. Fast-growing r-strategists using up nutrients already present in the water column do not use nitrate for fast growth, Only when overdosing carbohydrates nitrate will be used.