Denitrifying Bacteria and Rock Size

[NY_Caveman]

Let us assume one is using porous live rock to set up a minimalist aquascape. If one wants to maximize their anaerobic bacteria population is the size of the rock important? Is there a minimum size needed? Can rubble or rock sizes of 2-3 inches suffice? Or, is this the wrong way to look at it and size only appears to matter because a large rock may have areas subject to less flow and therefore areas with low oxygen.

 

[Flippers4pups]

Let us assume one is using porous live rock to set up a minimalist aquascape. If one wants to maximize their anaerobic bacteria population is the size of the rock important? Is there a minimum size needed? Can rubble or rock sizes of 2-3 inches suffice? Or, is this the wrong way to look at it and size only appears to matter because a large rock may have areas subject to less flow and therefore areas with low oxygen.

Minimalistic is a good look. I built my latest system that way. Don't think there's really a guide line on size of rock and how many pounds/size, but I did fill a good portion of my sump with extra rock. It's really up to you.

 

[NY_Caveman]

Minimalistic is a good look. I built my latest system that way. Don't think there's really a guide line on size of rock and how many pounds/size, but I did fill a good portion of my sump with extra rock. It's really up to you.

Planning to do the same in a back chamber. It is a 30 AIO.

 

[Flippers4pups]

Planning to do the same in a back chamber. It is a 30 AIO.

Your nutrient levels and how consistent they are will tell you if you need more later. N03 wise.

 

[NY_Caveman]

And to be clear I am not asking about the total amount of rock, but wondering if I should have a couple of larger sized rocks. Most of what I currently have is shelf, rubble and a couple of small rocks. I will add some live rock in the near future and am thinking about sizes.

 

[Flippers4pups]

And to be clear I am not asking about the total amount of rock, but wondering if I should have a couple of larger sized rocks. Most of what I currently have is shelf, rubble and a couple of small rocks. I will add some live rock in the near future and am thinking about sizes.

Well it would be up to what corals you want to keep and how many. Placement and grow out is also a consideration.

 

[Pmj]

Put siporax in the back chambers imo.

 

[NY_Caveman]

I guess my real intent is to better understand how to promote denitrifying bacteria. It led me to wonder how important the size of the rock is. In my case the tank is not set up yet, but soon. I am nearing the time to buy live rock. I should mention in this case the tank will be bare bottom and high flow.

My research showed a few who recommended Siporax and also Marine Pure blocks. They have their pros and cons, but I may consider that as the bioload increases.

 

[Randy Holmes-Farley Verified Community Expert]

Let us assume one is using porous live rock to set up a minimalist aquascape. If one wants to maximize their anaerobic bacteria population is the size of the rock important? Is there a minimum size needed? Can rubble or rock sizes of 2-3 inches suffice? Or, is this the wrong way to look at it and size only appears to matter because a large rock may have areas subject to less flow and therefore areas with low oxygen.

I don't think we know, in general, how far into typical reef rocks the biological processes are operating at significant levels, so can't answer if sock size matters.

 

[LPStandard]

I don't think we know, in general, how far into typical reef rocks the biological processes are operating at significant levels, so can't answer if sock size matters.

Sock size depends on the size of your feet! Of course it matters

 

[Randy Holmes-Farley Verified Community Expert]

Sock size depends on the size of your feet! Of course it matters

lol

 

[NY_Caveman]

I don't think we know, in general, how far into typical reef rocks the biological processes are operating at significant levels, so can't answer if sock size matters.

Makes sense.

I was thinking of it this way, take a chunk of hypothetical live rock that is a 5x5x5” cube (125” cubed). Then take 16 chunks of rubble rock that are roughly 2x2x2” that sum up to 125” cubed. I would intuitively think the large, single rock has greater potential for anaerobic bacteria growth, but infer from your post this may not be so. Of course there are many, many other variables involved.

 

[LPStandard]

lol

Couldn't resist! I prefer Darn Tough socks myself

hahaha ok, I'm done now.

 

[Belgian Anthias]

I guess my real intent is to better understand how to promote denitrifying bacteria. It led me to wonder how important the size of the rock is. In my case the tank is not set up yet, but soon. I am nearing the time to buy live rock. I should mention in this case the tank will be bare bottom and high flow.

My research showed a few who recommended Siporax and also Marine Pure blocks. They have their pros and cons, but I may consider that as the bioload increases.

Most denitrification takes place in a biofilm, any biofilm! Denitrification is done by heterotrops and autotrops. First of all space is needed for biofilms to grow. On the outer layers of the biofilm oxygen is consumed ( nitrification?) in such quantities that in the middle layers of the biofilm and certainly on the substrate not enough oxygen can be provided forcing bacteria to use an anaerobic pathway and reduce nitrate by using its oxygen producing nitrogen gas N2. Denitrification is limited to the oxygen minimum zone ( OMZ) in the biofilm for autotropic denitrification and to anoxic zones for heterotropic debnitrification , to usable organic carbon availability and to available sulphur compounds. Inside the biofilm the organic material for the heterotrops is provided by the normal decay and recycling rate as are the sulphur compounds which are the normal by-products of the recycling process. The sulphur compounds are used by autotrops to reduce nitrate to N2 , using the oxygen, and produce sulphate and or elemental sulphur.

Promoting denitrification is done by providing enough space for anaerobic activity , influencing the availability of usable organic carbon and or the availability of usable sulphur.
The size of the rock will matter but live rock has a low denitrification capacity due to the very low water transfer within the rock.

Why use expensive stuff when a normal cheap biofilter will be able to do the same a lot better?