A Seagrass and Deep Sand Bed Theory...

[VR28man]

Re: the OP - depends what we're trying to do and why we think a dsb will "solve" what problem.

(note I haven't read the paper cited by Randy, nor have I yet read in full subsea's post; they might cause me to modify my thinking.

The thread has also inspired me to reread https://chucksaddiction.thefishestate.net/seagrass.html)



Simplified, we are trying to keep a range of water parameters in our tanks, and control the growth of unwanted organisms - both within certain ranges. A life rock only tank, a soft coral tank, a mixed reef, and an acropora tank have a different range of desired parameters.

We can use any or all of the following methods.

1. microbiome management (stability in microorganisms prevents cycles of dinoflagellates, cyanobacteria, microalgae, etc.)
2. nitrification - the removal of ammonia, traditionally done in freshwater tanks and carried over into marine tanks, by bacterial conversion into nitrite, nitrate.
3. nutrient removal - by one or (more commonly) a combination of water changes, various media (e.g. active carbon, GFO), mechanisms (skimmer most famously in reefing; but also filter socks, ozone and UV among others), denitrification (denitrifying bacteria on various media, DSBs), growing other things and then removing them, or just having straight up areas for stuff to decay and be eaten (the not-too-often-used cryptic refugium).

I'd also add that "growing other things and then removing them" has a hiearchy, in that some things will grow faster and often trump other things. In my recollected order of what generally outcompetes other things:

- GHA (used as a filter in an algae turf scrubber, or unintentionally grown in the tank and hopefully exported by herbivores)
- chaeto (in a refugium or a chaeto reactor)
- most species of caulerpa and ulva (in reactor or fuge)
- gracillaria and other macro algae (reactor or fuge)
- merman's shaving brush, halimeda (more ornamental than anything else in our usage)
- Xenia (xenia fuges are a thing; some propose them as excellent ways to get rid of DOC)
- [I think seagrasses would go here]
- [mangroves would go here]
- [I assume other soft corals?]
- Acropora, Montipora, and otehr SPS [people have used this flippantly to emphasize the point that SPS use nutrients, which is why a tank with large and well established colonies can absorb lots of nutrients and be quite stable]



So amid all this, where do stand with DSBs and seagrass?

The DSB was meant to be a location for microfaunal stability and at the very least nitrogen absorbtion. That said, if you keep putting nutrients into it as basically a dumping ground, it seems to me (and sort of confirmed by my recollection of the controversy on DSBs) that it eventually becomes a composting area/landfill. [seafill?].

This is theoretically good for seagrass, but only to a certain point.

I'd also add that
- I'm now sure how well a seagrass refugium would work versus known mechanisms like an ATS (e.g. from Santa Monica Filtration), a macroalgae reactor or a macroalgae refugium.

- In nature, many photosynthetic seagrass beds (at least in an estuary or lagoon environment) face the direction of (i.e. absorb) riverborne nutrients coming into the sea. Though oftentimes some corals live among them - to include some kinds of LPS and softies! - they generally a good distance away from coral reefs proper, which generally have much more flow and lower amounts of nutrients.

(note that mesophotic seagrass beds are a completely different story, though IIRC there are ones that have both tracyphylia, deepwater seagrass and deepwater halimeda species)

I do hope someday to combine a display acro tank linked to a display seagrass refugium. (shallow lagoon seagrass!) But based on what I've heard I am concerned that the requirements (N/P/DOC levels, chemical warfare, nutrient import/export) for those to thrive would be divergent in a way that can't be resolved by having them in seperate connected tanks. (i.e. i fear that the heavy in and heavy out process and desired range of those parameters for acros might be too little for seagrass). I also fear that they will not be complimentary, but such a system might require at the very least heavy N and P supplementation.

In sum, I'm inclined to think seagrass is better as its own kind of biotope (marine planted tank?) tank vs a kind of refugium.

 

[VR28man]

@Subsea will read, and then think about your posts prior to any further responses. Generally, I'm sympathetic and would like to emulate your approach.

But I had to ask about this one.

@Greatreefer

When you speak of outdated filtration method, let’s address that. I choose to produce in tank live food to feed hungry mouths using sandbeds & cryptic sponges that process DOC 5 fold more efficiently than activated carbon which processes DOC 4 fold more efficiently than protein skimmers.

When John Tullock wrote the Natural Reef Aquarium my favorite quote was “Less Technology / More biology”.

so you're saying the sandbeds and cryptic critters are 20x more effective than protein skimmers? . (I assume the 5x and 4x are rhetorical and based on rough observation, I'm not here asking for proof of that number. )

Tullock's book to this day is outstanding. A modernized version of it would be even better.

 

[VR28man]

I don't know about the validity of the cleaning of sand beds by sea grasses, but this paper just came out, indicting that sea grass can actually grow in the absence of N sources by fixing nitrogen itself (via bacteria in its roots). So it need not take up N from a sand bed:

A seagrass harbours a nitrogen-fixing bacterial partner

Root-dwelling microbes help seagrasses to obtain nitrogen.

www.nature.com

Thanks, @Randy Holmes-Farley ! Unfortunately the article is paywalled. In summary (I think most relevant for this): from what you're saying, the N does not need to be from the sandbed, but bacteria living in the root can process N that's in the water column?

 

[Subsea]

@Subsea will read, and then think about your posts prior to any further responses. Generally, I'm sympathetic and would like to emulate your approach.

But I had to ask about this one.



so you're saying the sandbeds and cryptic critters are 20x more effective than protein skimmers? . (I assume the 5x and 4x are rhetorical and based on rough observation, I'm not here asking for proof of that number. )

Tullock's book to this day is outstanding. A modernized version of it would be even better.

Specifically DOC processing.

Ken Feldermen research on carbon dosing in reef tanks, posted in Advanced Aquaria, nailed down that activated carbon removed 80% of DOC compared to 20% removed by the best protein skimmers.

Recent research by Dutch scientist on the “Sponge Loop” documented amount of DOC & POC moved up the food chain by the “microbial loop” feed by the “Sponge Loop”.

https://www.reef2reef.com/threads/nutrient-management-by-“old-school”-reefer.784640/

This tread links research papers.

 

[Subsea]

I don't know about the validity of the cleaning of sand beds by sea grasses, but this paper just came out, indicting that sea grass can actually grow in the absence of N sources by fixing nitrogen itself (via bacteria in its roots). So it need not take up N from a sand bed:

A seagrass harbours a nitrogen-fixing bacterial partner

Root-dwelling microbes help seagrasses to obtain nitrogen.

www.nature.com

@Randy Holmes-Farley

Didn’t you write an article on how Cynobacteria converted inorganic phosphate into organic phosphate. Also, don’t some cynobacteria have nitrogen fixation capabilities.

 

[Subsea]

Re: the OP - depends what we're trying to do and why we think a dsb will "solve" what problem.

(note I haven't read the paper cited by Randy, nor have I yet read in full subsea's post; they might cause me to modify my thinking.

The thread has also inspired me to reread https://chucksaddiction.thefishestate.net/seagrass.html)



Simplified, we are trying to keep a range of water parameters in our tanks, and control the growth of unwanted organisms - both within certain ranges. A life rock only tank, a soft coral tank, a mixed reef, and an acropora tank have a different range of desired parameters.

We can use any or all of the following methods.

1. microbiome management (stability in microorganisms prevents cycles of dinoflagellates, cyanobacteria, microalgae, etc.)
2. nitrification - the removal of ammonia, traditionally done in freshwater tanks and carried over into marine tanks, by bacterial conversion into nitrite, nitrate.
3. nutrient removal - by one or (more commonly) a combination of water changes, various media (e.g. active carbon, GFO), mechanisms (skimmer most famously in reefing; but also filter socks, ozone and UV among others), denitrification (denitrifying bacteria on various media, DSBs), growing other things and then removing them, or just having straight up areas for stuff to decay and be eaten (the not-too-often-used cryptic refugium).

I'd also add that "growing other things and then removing them" has a hiearchy, in that some things will grow faster and often trump other things. In my recollected order of what generally outcompetes other things:

- GHA (used as a filter in an algae turf scrubber, or unintentionally grown in the tank and hopefully exported by herbivores)
- chaeto (in a refugium or a chaeto reactor)
- most species of caulerpa and ulva (in reactor or fuge)
- gracillaria and other macro algae (reactor or fuge)
- merman's shaving brush, halimeda (more ornamental than anything else in our usage)
- Xenia (xenia fuges are a thing; some propose them as excellent ways to get rid of DOC)
- [I think seagrasses would go here]
- [mangroves would go here]
- [I assume other soft corals?]
- Acropora, Montipora, and otehr SPS [people have used this flippantly to emphasize the point that SPS use nutrients, which is why a tank with large and well established colonies can absorb lots of nutrients and be quite stable]



So amid all this, where do stand with DSBs and seagrass?

The DSB was meant to be a location for microfaunal stability and at the very least nitrogen absorbtion. That said, if you keep putting nutrients into it as basically a dumping ground, it seems to me (and sort of confirmed by my recollection of the controversy on DSBs) that it eventually becomes a composting area/landfill. [seafill?].

This is theoretically good for seagrass, but only to a certain point.

I'd also add that
- I'm now sure how well a seagrass refugium would work versus known mechanisms like an ATS (e.g. from Santa Monica Filtration), a macroalgae reactor or a macroalgae refugium.

- In nature, many photosynthetic seagrass beds (at least in an estuary or lagoon environment) face the direction of (i.e. absorb) riverborne nutrients coming into the sea. Though oftentimes some corals live among them - to include some kinds of LPS and softies! - they generally a good distance away from coral reefs proper, which generally have much more flow and lower amounts of nutrients.

(note that mesophotic seagrass beds are a completely different story, though IIRC there are ones that have both tracyphylia, deepwater seagrass and deepwater halimeda species)

I do hope someday to combine a display acro tank linked to a display seagrass refugium. (shallow lagoon seagrass!) But based on what I've heard I am concerned that the requirements (N/P/DOC levels, chemical warfare, nutrient import/export) for those to thrive would be divergent in a way that can't be resolved by having them in seperate connected tanks. (i.e. i fear that the heavy in and heavy out process and desired range of those parameters for acros might be too little for seagrass). I also fear that they will not be complimentary, but such a system might require at the very least heavy N and P supplementation.

In sum, I'm inclined to think seagrass is better as its own kind of biotope (marine planted tank?) tank vs a kind of refugium.

kudos to the above. You should consider writing a r2r article. It’s been years since I have been to this Chuck’s Addiction site. Thank you for bringing it to light.

 

[Randy Holmes-Farley]

Thanks, @Randy Holmes-Farley ! Unfortunately the article is paywalled. In summary (I think most relevant for this): from what you're saying, the N does not need to be from the sandbed, but bacteria living in the root can process N that's in the water column?

Yes, from N2 in the water. it need not take up any nutrient forms of N.

 

[Randy Holmes-Farley]

@Randy Holmes-Farley

Didn’t you write an article on how Cynobacteria converted inorganic phosphate into organic phosphate. Also, don’t some cynobacteria have nitrogen fixation capabilities.

Yes, cyanobacteria can fix nitrogen, and all photosynthetic organisms (algae, corals, trees, etc) can to up inorganic phosphate and make organophosphates such as phospholipids, DNA, etc..

 

[Subsea]

Yes, cyanobacteria can fix nitrogen, and all photosynthetic organisms (algae, corals, trees, etc) can to up inorganic phosphate and make organophosphates such as phospholipids, DNA, etc..

Entrapped Sediments as a Source of Phosphorus in Epilithic Cyanobacterial Proliferations in Low Nutrient Rivers

Proliferations of the benthic mat-forming cyanobacteria Phormidium have been reported in rivers worldwide. Phormidium commonly produces natural toxins which pose a health risk to animal and humans. Recent field studies in New Zealand identified that sites with Phormidium proliferations...

journals.plos.org

This article touches how Cynobacteria mats dissolve calcium phosphate sediments.

 

[Greatreefer]

@Greatreefer
Cannister filters are handily used between tanks as required. I use them to cycle tanks and of recent as an instant source of transferring biodiversity of pods & cryptic sponges.

When you speak of outdated filtration method, let’s address that. I choose to produce in tank live food to feed hungry mouths using sandbeds & cryptic sponges that process DOC 5 fold more efficiently than activated carbon which processes DOC 4 fold more efficiently than protein skimmers.

When John Tullock wrote the Natural Reef Aquarium my favorite quote was “Less Technology / More biology”.

Build thread is in my signature, but let’s talk here.

The undergravel filter is a competitor of macro algae, but it does much more. It grows detrivores whose larva feed corals. As a Laissez Faire reefkeeper and an organic gardner I choose to use simple natural systems that integrate bacteria, algae & sponge recycling.
Instead of high alkalinity demanding SPS, I choose other filter feeders like ornamental sponges, flame scallops and sea apples with a mixed garden of softies. I allow night time pH swings to lower pH which contributes to passive alkalinity buffering and trace mineral addition. I have not changed water in several years, but plan to change 100% volume over a 7 day period this year.. It’s cheaper than ICP testing.

Dude, this is incredible. This is what makes this hobby so cool is the bio diversity and the puzzle of how off all fits together snd can work in harmony.
Id love to pick your brain more. On this topic because im looking at rebuilding my system. I was thinking about trying my hand at ornamental sponges and gargonians along with some macro algae. Sounds like you and I need to have more conversations about filtration systems. Would you mind if I PMd you so we could talk more in-depth?
Thanks for all the info!

 

[Subsea]

@Greatreefer,

Of course you can message me. Give me the link on your build thread and we can confer there as well.

However, I would also prefer a discussion on this thread in Reef discussion forum:

https://www.reef2reef.com/threads/nutrient-management-by-“old-school”-reefer.784640/

There are many informed members on this thread. I like open discussion with the community. We can all contribute knowledge and hopefully wisdom.

After 50 yrs of Reefing, I have found that natural systems reflect my understanding that the Coral Holibiont is interconnected & interdependent on each parts of the community. We nurture what we love and I see beauty in how it works and seek more knowledge and in so doing, I emulate nature.

As many naturalists and environmentalists have suggested, we should set aside our arrogance,
our desire to conquer and control everything, and walk hand in hand with Mother Nature. -Walter Adey

 

[Greatreefer]

@Greatreefer,

Of course you can message me. Give me the link on your build thread and we can confer there as well.

However, I would also prefer a discussion on this thread in Reef discussion forum:

https://www.reef2reef.com/threads/nutrient-management-by-“old-school”-reefer.784640/

There are many informed members on this thread. I like open discussion with the community. We can all contribute knowledge and hopefully wisdom.

After 50 yrs of Reefing, I have found that natural systems reflect my understanding that the Coral Holibiont is interconnected & interdependent on each parts of the community. We nurture what we love and I see beauty in how it works and seek more knowledge and in so doing, I emulate nature.

As many naturalists and environmentalists have suggested, we should set aside our arrogance,
our desire to conquer and control everything, and walk hand in hand with Mother Nature. -Walter Adey

As far as build threads go, I don't have one yet mainly because all I have is an idea and a very basic parts list. However, once I get the parts, I may actually post my 1st build thread.

In regarding your reverse undergravel filter, are you running this with a sump or as a stand alone undergravel filter?
The system im looking to build is a 33gallon long with magrove trees on one end.
(Post pics later)
In regards to filtration: what my original plan was to mod a 20L and turn it into a three chambered sump. Center chamber was going to be a fuge and where I could grow macro algaes and bugs.
Now I'm thinking about just using the tank without the bulk heads and throwing a bunch of rock and sand with no skimmer and no filter socks.

 

[Subsea]

As far as build threads go, I don't have one yet mainly because all I have is an idea and a very basic parts list. However, once I get the parts, I may actually post my 1st build thread.

In regarding your reverse undergravel filter, are you running this with a sump or as a stand alone undergravel filter?
The system im looking to build is a 33gallon long with magrove trees on one end.
(Post pics later)
In regards to filtration: what my original plan was to mod a 20L and turn it into a three chambered sump. Center chamber was going to be a fuge and where I could grow macro algaes and bugs.
Now I'm thinking about just using the tank without the bulk heads and throwing a bunch of rock and sand with no skimmer and no filter socks.

on 5yr old 120G tank, display has reverse flow UG filter with 2” deep sand bed. Cryptic refugium is bare 40G breeder tank. Detritus on bottom glass is 3/8” thick and is flush with top of eggcrate spacer to keep living rock out of the mud. Adding another layer of eggcrate before I fill with porous dead rock to inoculate more rock is on my to “do list”. My initial business model with 20’ by 40’ greenhouse and 10K gallons of tanks was to make living rock from Texas Holy limestone rock using diver collected rock from GLR.

 

[Subsea]

In regarding your reverse undergravel filter, are you running this with a sump or as a stand alone undergravel filter?

@Greatreefer
At present, I have four systems with three having RFUG filters with 2” of aragonite. The 75G at 25 years mature and the 120G at 5 years mature both have cryptic refugiums that are 5 years mature. I showed pictures of 40G breeder. The 55G at 6 months mature has two canister filters with reef rubble acting as hi-flow cryptic refugiums.

The last system is 30G high tank at 6 month mature. It has a 2” aroggonite sandbed seeded with 15 pounds of diver collected live sand and 15 pounds of diver collected living rock. Both the 30G & 55G were set up to be ornamental seaweed lagoon mixed garden.

 

[Greatreefer]

to build your your cryptic fuge, you placed some eggcrate and the" miracle mud" aka Iron based FW plant substrate along with some live rock in the sump. Does the live rock sit on top of the eggcrate to elevate the rock off the substrate or does this really matter. I also noticed you have your return up elevated off the bottom of the sump with some kind of guard on the intake. Is the reason for the elevation because you don't want to disturb the cryptic zone. In regards to the drain could I just pile up a bunch of rocks right under the drain line to help cut down on mirco bubbles?

 

[Subsea]

@Greatreefer
Live rock sits above mud. Eventually detritus/MULM builds up and is the incubator for the microbial loop which moves live food (organic carbon) up the food chain.

Cryptic refugium can be unlight sump. With introduction of cryptic sponges, the third leg of biochemistry (algae & bacteria are other two) cryptic sponges, converts DOC into detritus which feeds the microbial loop.

PS: On 40G bare bones cryptic refugium, initially this was used as Chaeto macro refugium and pump required strainer to prevent Chaeto from clogging up pump. I think stacking rubble under water in is a good method to assist with gas exchange.

 

[Greatreefer]

@Greatreefer
Live rock sits above mud. Eventually detritus/MULM builds up and is the incubator for the microbial loop which moves live food (organic carbon) up the food chain.

Cryptic refugium can be unlight sump. With introduction of cryptic sponges, the third leg of biochemistry (algae & bacteria are other two) cryptic sponges, converts DOC into detritus which feeds the microbial loop.

PS: On 40G bare bones cryptic refugium, initially this was used as Chaeto macro refugium and pump required strainer to prevent Chaeto from clogging up pump. I think stacking rubble under water in is a good method to assist with gas exchange.

how long does it take to build up an efficient cryptic zone?
If I were to start one from scratch, where would be a good place to stock up on these critters?

 

[Subsea]

Buy diver collected live rock and if you are near a hub, get next day air freight minimizing dieoff & maximizing biodiversity. Sometimes on mature tanks, while moving aquascaping around, I find cryptic sponges on back side.

How long? Too many variable to attempt an answer. Efficiency depends on how you define it. You will not see nutrient reduction results. This is a nutrient recycling process, similarly an organic Gardner would tell you ”they are not growing vegetable, they are growing soil“. I use bioindicators like micro feather dusters and noted growth everywhere after initiating cryptic sponge refugium.

Steve Tyree, who first proposed cryptic zone filtration has on line books on this subject. His company, reeffarmers used to sell this stuff. In a few months I may have much inoculated for another day.

 

[Greatreefer]

Buy diver collected live rock and if you are near a hub, get next day air freight to maximize biodiversity. Sometimes will moving aquascaping around, I find cryptic sponges on back side.

Ive ordered uncurred live rock before and have gotten some very terrifying results from it. So I think what I'll do is eventually be taking down my 5 year old reef and move most of the rock and sand into the new system hopefully, doing this will help build up those critters. If needed, I can also order from a place called indo pacific sea farm. They have some cool stuff too.

 

[Subsea]

Ive ordered uncurred live rock before and have gotten some very terrifying results from it. So I think what I'll do is eventually be taking down my 5 year old reef and move most of the rock and sand into the new system hopefully, doing this will help build up those critters. If needed, I can also order from a place called indo pacific sea farm. They have some cool stuff too.

I just ordered from IPSF with delivery next week. I ordered their mix & match special to get their variety of Sea Grapes for my human consumption. Thank you @Wheat Toast for encouragement by your success. Ten yrs ago I bought two pounds of Red Ogo from Gerald to start up growout in 10K gallon system in a 20’ by 40’ greenhouse. This was to supply Asian restaurants with fresh Red Ogo. Unfortunately, Aquifier makeup was high in sulfur which carried over into the taste.