More live rock, less nitrate?

[klavmaister]

I know quite a bit about ls, certainly not everything. Does living rock convert nitrate to gas? or does live rock only convert ammonia and nitrite? What I wonder is whether more ls or ceramic plates can in theory reduce nitrate/ make skimmers unnesesary. example is a 250l aquarium, and a sump packed with stone/ceramic slabs

 

[Randy Holmes-Farley Verified Community Expert]

Live rock has a variety of processes that can take place on ammonia, including uptake into organisms such as bacteria and algae, conversion to nitrite and nitrate, and conversion to N2.

That said, IMO the primary utility of a skimmer is not nutrient reduction, but rather export of organic matter and aeration. Even in a low nutrient system where one doses N and/or P, I would not turn off a skimmer.

 

[Kenneth Wingerter]

One could hardly make sweeping generalities based on this, but it is nonetheless interesting. https://reefs.com/new-study-live-rock-doesnt-really-denitrify/

Some researchers suggest that the highest rates of denitrification actually occur within medium to course (that is, not fine) sand/gravel beds. https://www.int-res.com/articles/meps/80/m080p075.pdf

What I get from all this is that water flow is very important here. So, restricted enough that anaerobic zones may persist, but also strong enough to allow for adequate exchange of NO3/N2 and other metabolites. Perhaps large chunks (i.e., live rock) and fine, packed sand both restrict water flow too much, and the optimal environment lies somewhere in between. (Denitrification is proposed to occur within the porous bits of chunky gravel, with the pore waters moving vigorously around them.)

The effectiveness of your ceramic biomedia similarly may depend upon its porosity and the strength of water flow around/through it.