Is sand alone enough for biological filtration?

[josh1591]

Okay so I want to gather some opinions. I'm thinking about getting this small frag tank (https://www.pnw-custom.com/product-page/12in-lagoon-frag-tank). Considering the size of the tank there is not much room for lots of biological filtration. I am wondering if I put live sand into the bottom, would that be enough to host bacteria for the breakdown of waste? I would probably have no fish and just feed the corals, so the only nutrients coming in would be from the coral food. It would also be cool if I could just put the frags directly on the sand, throw in tons of copepods to sort of roam around, and help keep the frags clean. Is this possible?

 

[KrisReef]

No fish, no huge biological load, no rocks or sand needed?

 

[Tired]

Seems entirely doable if you just have frags.

Worth remembering that many corals don't especially like to have their flesh touching the sand. Other than that, should work out fine.

 

[bushdoc]

With no fish in a system, possibly. Some put bio-media in frag tanks and that’s what I would recommend.You could always remove them one by one if its too much.

 

[HudsonReefer2.0]

Seems entirely doable if you just have frags.

Worth remembering that many corals don't especially like to have their flesh touching the sand. Other than that, should work out fine.

They don’t like sand in their bathing suits either. Lol

 

[josh1591]

No fish, no huge biological load, no rocks or sand needed?

There would be some nutrients from coral food so what would help break down the waste?

 

[josh1591]

Seems entirely doable if you just have frags.

Worth remembering that many corals don't especially like to have their flesh touching the sand. Other than that, should work out fine.

Sorry I should have specified, they would be zoanthid frags and I would cut the stem off the plug and lay the disk onto the sand.

 

[vetteguy53081]

Okay so I want to gather some opinions. I'm thinking about getting this small frag tank (https://www.pnw-custom.com/product-page/12in-lagoon-frag-tank). Considering the size of the tank there is not much room for lots of biological filtration. I am wondering if I put live sand into the bottom, would that be enough to host bacteria for the breakdown of waste? I would probably have no fish and just feed the corals, so the only nutrients coming in would be from the coral food. It would also be cool if I could just put the frags directly on the sand, throw in tons of copepods to sort of roam around, and help keep the frags clean. Is this possible?

In part it supports bacteria but bilogical filtration refers to when bacteria in your tank eat compounds such as ammonia, nitrite or nitrate, and converts it into something else. The use of live rock is one of the best ways to provide biological filtration for the tank. Nitrifying bacteria lives in the sand and can also exist on surfaces such as sponges, biocall, ceramic chips and bio-balls.
It is cycling that helps get the bacteria established- Not the sand

 

[josh1591]

In part it supports bacteria but bilogical filtration refers to when bacteria in your tank eat compounds such as ammonia, nitrite or nitrate, and converts it into something else. The use of live rock is one of the best ways to provide biological filtration for the tank. Nitrifying bacteria lives in the sand and can also exist on surfaces such as sponges, biocall, ceramic chips and bio-balls.
It is cycling that helps get the bacteria established- Not the sand

I currently have cycled live rock rubble. I could throw that into the filter compartment. But I'm wondering if the sand could eventually be considered "cycled" and promote enough nitrifying bacteria alone to run the tank off of.

 

[Mr. Mojo Rising]

it would take a deep sand bed, 6" or more, and it will take time for the 3 aerobic layers to form. It also needs plankton living in the sand to physically move grains of sand around.

I'm just simplifying it cause I can't explain it better, but it takes research and time and understanding, its not just about adding sand, that won't do anything for biofiltration in the short term

 

[josh1591]

it would take a deep sand bed, 6" or more, and it will take time for the 3 aerobic layers to form. It also needs plankton living in the sand to physically move grains of sand around.

I'm just simplifying it cause I can't explain it better, but it takes research and time and understanding, its not just about adding sand, that won't do anything for biofiltration in the short term

So you're saying without a deep sand bed there really isn't a significant amount of biological activity going on?

 

[vetteguy53081]

I currently have cycled live rock rubble. I could throw that into the filter compartment. But I'm wondering if the sand could eventually be considered "cycled" and promote enough nitrifying bacteria alone to run the tank off of.

Not necessarily as sand promotes both aerobic and anaerobic bacteria helping to break down waste and remove nitrates. The deeper the sand bed, the less effective this becomes. Aged sand does not supply the needed bacteria alone to support waste reduction. This is why we periodically siphon sand to allow removal of detritus and supply oxygen to the bacteria.

 

[Mr. Mojo Rising]

So you're saying without a deep sand bed there really isn't a significant amount of biological activity going on?

thats right, its aesthetics only.

 

[edd59]

very doable with an under gravel filter. that was our main filtration in the day, before live rock.

 

[Nano sapiens]

Okay so I want to gather some opinions. I'm thinking about getting this small frag tank (https://www.pnw-custom.com/product-page/12in-lagoon-frag-tank). Considering the size of the tank there is not much room for lots of biological filtration. I am wondering if I put live sand into the bottom, would that be enough to host bacteria for the breakdown of waste? I would probably have no fish and just feed the corals, so the only nutrients coming in would be from the coral food. It would also be cool if I could just put the frags directly on the sand, throw in tons of copepods to sort of roam around, and help keep the frags clean. Is this possible?

Yes. Live aragonite sand can be very effective at both nitrification and denitrification. Maintenance is key (at least occasional sand stirring/excess detritus removal).

 

[KrisReef]

I currently have cycled live rock rubble. I could throw that into the filter compartment. But I'm wondering if the sand could eventually be considered "cycled" and promote enough nitrifying bacteria alone to run the tank off of.

That will depend upon how much food you add to the system that either rots or gets eaten and digested. If inputs are low then you don’t need a ton of surface area to support a biological digestive system. Water changes and filter sock cleaning can handle much along the way.

 

[KrisReef]

very doable with an under gravel filter. that was our main filtration in the day, before live rock.

I just saw that ug filters were on sale, online at PetCo.
The old technology can still be functional.

 

[sixty_reefer]

Okay so I want to gather some opinions. I'm thinking about getting this small frag tank (https://www.pnw-custom.com/product-page/12in-lagoon-frag-tank). Considering the size of the tank there is not much room for lots of biological filtration. I am wondering if I put live sand into the bottom, would that be enough to host bacteria for the breakdown of waste? I would probably have no fish and just feed the corals, so the only nutrients coming in would be from the coral food. It would also be cool if I could just put the frags directly on the sand, throw in tons of copepods to sort of roam around, and help keep the frags clean. Is this possible?

There is folks running QT with just glass and plastic fittings as surface area for bacteria. That should answer your question

 

[Nano sapiens]

it would take a deep sand bed, 6" or more, and it will take time for the 3 aerobic layers to form. It also needs plankton living in the sand to physically move grains of sand around.

I'm just simplifying it cause I can't explain it better, but it takes research and time and understanding, its not just about adding sand, that won't do anything for biofiltration in the short term

In the interest of clarity, let's look at this in more detail.

Even a shallow 1-2" live aragonite sand bed will perform nitrification and denitrification in a typical reef aquarium. If you were to blow up a single live sand grain to the size of a small country, you'd basically see that the exterior is coated with nitrifiers (they'd have access to high oxygenation) and the interior with denitrifiers (anoxic or low oxygen conditions). The bacteria types are 'coupled', meaning they are in close proximity to each other and can efficiently process the products associated with the nitrogen cycle. You also get stratification of the aerobic, anoxic and anaerobic layers when the sand is not too shallow (~1" -3" with typical medium flow), but much more is doable with a substantial population of sand stirring infauna, but has other risks that have contributed to making deep sand beds less popular (mainly, depleted oxygen during power outages and unsightly appearance).

The area of a typical reef aquarium sand bed is substantial when you consider each grain's surface area (typically much more surface area for nitrification/denitrification than the live rock). One of live rock's 'claim to fames' is that along with some nitrification/denitrification it hosts bio films/periphyton that efficiently remove detritus particles, algae spores, bacteria/archaea/fungi, etc. which in turn provides water clarity (among other benefits).

While benthic organisms do move sand grains around (aka 'bioturbation'), the main movement associated with substances entering the substrate is from a physical process called 'advection' and is brought about by water flow. A secondary process is 'diffusion', but it is typically orders of magnitude less effective in a reef system.

So the short answer is, 'Yes', live aragonite sand can nitrify and denitrify quite well

 

[Subsea]

In the interest of clarity, let's look at this in more detail.

Even a shallow 1-2" live aragonite sand bed will perform nitrification and denitrification in a typical reef aquarium. If you were to blow up a single live sand grain to the size of a small country, you'd basically see that the exterior is coated with nitrifiers (they'd have access to high oxygenation) and the interior with denitrifiers (anoxic or low oxygen conditions). The bacteria types are 'coupled', meaning they are in close proximity to each other and can efficiently process the products associated with the nitrogen cycle. You also get stratification of the aerobic, anoxic and anaerobic layers when the sand is not too shallow (~1" -3" with typical medium flow), but much more is doable with a substantial population of sand stirring infauna, but has other risks that have contributed to making deep sand beds less popular (mainly, depleted oxygen during power outages and unsightly appearance).

The area of a typical reef aquarium sand bed is substantial when you consider each grain's surface area (typically much more surface area for nitrification/denitrification than the live rock). One of live rock's 'claim to fames' is that along with some nitrification/denitrification it hosts bio films/periphyton that efficiently remove detritus particles, algae spores, bacteria/archaea/fungi, etc. which in turn provides water clarity (among other benefits).

While benthic organisms do move sand grains around (aka 'bioturbation'), the main movement associated with substances entering the substrate is from a physical process called 'advection' and is brought about by water flow. A secondary process is 'diffusion', but it is typically orders of magnitude less effective in a reef system.

So the short answer is, 'Yes', live aragonite sand can nitrify and denitrify quite well

Kudos to this post.
I would estimate that 1 pound of aroggonite at 1-2mm grain size has at least a hundred fold more surface area than 1 pound of live rock. If compared to dense Bryozone limestone, live rock fron Florida, the surface area comparison will be much greater than 100 to 1.