I would like to build a new aquarium - approx. 150l hosting only anemones with maybe a few simple softies, a few shirmps, crabs and clownfish.
Filtration:
Hang of filter with biomedia
A little of activated carbon
A few macroalgae in the display tank
I wonder how much macro and micro would be consumed in such system without stony corals. I would like to avoid doing any water changes and maybe just replenish some of the chemicals from time to time (based on ICP test done once per a few months). I would just test NO3 and PO4 on a frequent basis to see if lack of skimmer isn't disturbing anything and maybe involve a very weak carbon dosing to stimulate the biology.
T be blunt, haveing BTAs that were acquired 10, 15 or 25 years ago and having a better understanding of the roles of DOC in reef systems I don't see a ssytem can be maintained for years without water changes to remove detrimental DOC.
T be blunt, haveing BTAs that were acquired 10, 15 or 25 years ago and having a better understanding of the roles of DOC in reef systems I don't see a ssytem can be maintained for years without water changes to remove detrimental DOC.
UVs don't remove DOC. In his presentaion at Next Wave 20ll in Dallas Charles Delbeek related testing done at the Steinhart Aquarium advised aquarists not to use OZone due to the inconsistancy of the equipment available to aquarists and the difficulty in maintining proper dosages. Additionally there are microbes that are ozone refractory, ie not killed by ozone. More importantly, over the last couple of decades a great deal of research has been done on the roles of DOC in promoting microbial growth in holobionts that can cause issues with corals (and anemones). This DOC can roughly be divided into labile, semi-refractory and refractory. The refractory component of DOC is usually not available for microbial growth but with the use of ozone it is broken down into labile forms that can then be used by microbes as a food source to reproduce potentially causing problems in animal holobionts by causing pathogenic shifts or hypoxic conditions with excessive population numbers.
Here's some links by scientists studying reef ecosystems you might find informative:
"Coral Reefs in the Microbial Seas" This video compliments Rohwer's book of the same title (Paper back is ~$20, Kindle is ~$10), both deal with the conflicting roles of the different types of DOC in reef ecosystems. While there is overlap bewteen his book and the video both have information not covered by the other and together give a broader view of the complex relationships found in reef ecosystems
Changing Seas - Mysterious Microbes
Microbial view of Coral Decline
Nitrogen cycling in hte coral holobiont
BActeria and Sponges
Maintenance of Coral Reef Health (refferences at the end)
Optical Feedback Loop in Colorful Coral Bleaching
DNA Sequencing and the Reef Tank Microbiome
And if you want to dig into the research a little more here's a data bomb.
Global microbialization of coral reefs - DDAM Proven
Analysis of 60 sites in three ocean basins suggests that overgrowth of fleshy algae on coral reefs supports higher microbial abundances dominated by copiotrophic, potentially pathogenic bacteria via the provision of dissolved inorganic carbon.
www.nature.com
Indirect effects of algae on coral: algae‐mediated, microbe‐induced coral mortality
Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant...
peerj.com
Role of elevated organic carbon levels and microbial activity in coral mortality
Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity
Algae releases significantly more DOC into the water than coral.
Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in...
journals.plos.org
Pathologies and mortality rates caused by organic carbon and nutrient stressors in three Caribbean coral species.
DOC caused coral death but not high nitrates, phosphates or ammonium.
Planar optodes were used to visualize oxygen distribution patterns associated with a coral reef associated green algae (Chaetomorpha sp.) and a hermatypic coral (Favia sp.) separately, as standalone organisms, and placed in close proximity mimicking coral-algal interactions. Oxygen patterns were...
peerj.com
Biological oxygen demand optode analysis of coral reef-associated microbial communities exposed to algal exudates
Exposure to exudates derived from turf algae stimulated higher oxygen drawdown by the coral-associated bacteria.
Algae-derived dissolved organic matter has been hypothesized to induce mortality of reef building corals. One proposed killing mechanism is a zone of hypoxia created by rapidly growing microbes. To investigate this hypothesis, biological oxygen ...
www.ncbi.nlm.nih.gov
Microbial ecology: Algae feed a shift on coral reefs
Human pressures on coral reefs are giving macroalgae a competitive advantage over reef-building corals. These algae support larger, and potentially pathogenic, microbial populations that are metabolically primed for less-efficient, yet faster, carbohydrate remineralization, perpetuating a...
www.nature.com
Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages.
Increasing algal cover on tropical reefs worldwide may be maintained through feedbacks whereby algae outcompete coral by altering microbial activity. We hypothesized that algae and coral release compositionally distinct exudates that differentially alter bacterioplankton growth and community...
www.ncbi.nlm.nih.gov
Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching
Elevated ammonium delays the impairment of the coral-dinoflagellate symbiosis during labile carbon pollution
(here's an argument for maintaining heavy fish loads if you're carbon dosing)
Labile dissolved organic carbon (DOC) is a major pollutant in coastal marine environments affected by anthropogenic impacts, and may significantly con…
www.sciencedirect.com
Excess labile carbon promotes the expression of virulence factors in coral reef bacterioplankton
Coastal pollution and algal cover are increasing on many coral reefs, resulting in higher dissolved organic carbon (DOC) concentrations. High DOC concentrations strongly affect microbial activity in reef waters and select for copiotrophic, often potentially virulent microbial populations. High...
www.nature.com
Unseen players shape benthic competition on coral reefs.
Recent work has shown that hydrophilic and hydrophobic organic matter (OM) from algae disrupts the function of the coral holobiont and promotes the invasion of opportunistic pathogens, leading to coral morbidity and mortality. Here we refer to these dynamics as the (3)DAM [dissolved organic...
www.ncbi.nlm.nih.gov
Allelochemicals Produced by Brown Macroalgae of the Lobophora Genus Are Active against Coral Larvae and Associated Bacteria, Supporting Pathogenic Shifts to Vibrio Dominance.
Diverse microbial communities associate with coral tissues and mucus, providing important protective and nutritional services, but once disturbed, the microbial equilibrium may shift from a beneficial state to one that is detrimental or pathogenic. Macroalgae (e.g., seaweeds) can physically and...
www.ncbi.nlm.nih.gov
Macroalgae decrease growth and alter microbial community structure of the reef-building coral, Porites astreoides.
With the continued and unprecedented decline of coral reefs worldwide, evaluating the factors that contribute to coral demise is of critical importance. As coral cover declines, macroalgae are becoming more common on tropical reefs. Interactions between these macroalgae and corals may alter the...
www.ncbi.nlm.nih.gov
Macroalgal extracts induce bacterial assemblage shifts and sublethal tissue stress in Caribbean corals.
Benthic macroalgae can be abundant on present-day coral reefs, especially where rates of herbivory are low and/or dissolved nutrients are high. This study investigated the impact of macroalgal extracts on both coral-associated bacterial assemblages and sublethal stress response of corals. Crude...
www.ncbi.nlm.nih.gov
Biophysical and physiological processes causing oxygen loss from coral reefs.
Because sponges are essential players in the carbon, nitrogen and phosphorus cycle(s) on reefs here's some links to research done with them.
Element cycling on tropical coral reefs.
This is Jasper de Geoij's ground breaking research on reef sponge finding some species process labile DOC 1000X faster than bacterioplankton. (The introduction is in Dutch but the content is in English.)
Marine sponges are ubiquitous colonizers of shallow, clear-water environments in the oceans (1, 2). Sponges have emerged as significant mediators of biogeochemical fluxes in coastal zones by virtue of respiring organic matter and facilitating both the consumption and release of nutrients (3, 4)...
www.pnas.org
Phosphorus sequestration in the form of polyphosphate by microbial symbionts in marine sponges
Coral reefs are highly productive ecosystems that raise a conundrum called “Darwin’s paradox”: How can high production flourish in low-nutrient conditions? We show here that in three abundant Caribbean sponges, the granules that have been commonly observed in sponge tissue for decades are...
www.pnas.org
Differential recycling of coral and algal dissolved organic matter via the sponge loop.
Sponges treat DOC from algae differently than DOC from corals
Coral reefs are economically important ecosystems that have suffered unprecedented losses of corals in the recent past. Why have Caribbean reefs in particu
academic.oup.com
Surviving in a Marine Desert The Sponge Loop Retains Resources Within Coral Reefs
Dissolved organic carbon and nitrogen are quickly processed by sponges and released back into the reef food web in hours as carbon and nitrogen rich detritus.
PDF | On Jun 23, 2015, Jasper M de Goeij and others published 2013 deGoeij Science Sponge loop | Find, read and cite all the research you need on ResearchGate
www.researchgate.net
Natural Diet of Coral-Excavating Sponges Consists Mainly of Dissolved Organic Carbon (DOC)
Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. ...
www.ncbi.nlm.nih.gov
The Role of Marine Sponges in Carbon and Nitrogen Cycles of COral Reefs and Nearshore Environments.
Explore millions of resources from scholarly journals, books, newspapers, videos and more, on the ProQuest Platform.
search.proquest.com
And since we're discussing favorable and not so favorable bacteria here's a paper looking at how different corals and polyps are influencing the bacteria in the water column.
Aura-biomes are present in the water layer above coral reef benthic macro-organisms
As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in...
UVs don't remove DOC. In his presentaion at Next Wave 20ll in Dallas Charles Delbeek related testing done at the Steinhart Aquarium advised aquarists not to use OZone due to the inconsistancy of the equipment available to aquarists and the difficulty in maintining proper dosages. Additionally there are microbes that are ozone refractory, ie not killed by ozone. More importantly, over the last couple of decades a great deal of research has been done on the roles of DOC in promoting microbial growth in holobionts that can cause issues with corals (and anemones). This DOC can roughly be divided into labile, semi-refractory and refractory. The refractory component of DOC is usually not available for microbial growth but with the use of ozone it is broken down into labile forms that can then be used by microbes as a food source to reproduce potentially causing problems in animal holobionts by causing pathogenic shifts or hypoxic conditions with excessive population numbers.
Here's some links by scientists studying reef ecosystems you might find informative:
"Coral Reefs in the Microbial Seas" This video compliments Rohwer's book of the same title (Paper back is ~$20, Kindle is ~$10), both deal with the conflicting roles of the different types of DOC in reef ecosystems. While there is overlap bewteen his book and the video both have information not covered by the other and together give a broader view of the complex relationships found in reef ecosystems
Changing Seas - Mysterious Microbes
Microbial view of Coral Decline
Nitrogen cycling in hte coral holobiont
BActeria and Sponges
Maintenance of Coral Reef Health (refferences at the end)
Optical Feedback Loop in Colorful Coral Bleaching
DNA Sequencing and the Reef Tank Microbiome
And if you want to dig into the research a little more here's a data bomb.
Global microbialization of coral reefs - DDAM Proven
Analysis of 60 sites in three ocean basins suggests that overgrowth of fleshy algae on coral reefs supports higher microbial abundances dominated by copiotrophic, potentially pathogenic bacteria via the provision of dissolved inorganic carbon.
www.nature.com
Indirect effects of algae on coral: algae‐mediated, microbe‐induced coral mortality
Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant...
peerj.com
Role of elevated organic carbon levels and microbial activity in coral mortality
Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity
Algae releases significantly more DOC into the water than coral.
Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in...
journals.plos.org
Pathologies and mortality rates caused by organic carbon and nutrient stressors in three Caribbean coral species.
DOC caused coral death but not high nitrates, phosphates or ammonium.
Planar optodes were used to visualize oxygen distribution patterns associated with a coral reef associated green algae (Chaetomorpha sp.) and a hermatypic coral (Favia sp.) separately, as standalone organisms, and placed in close proximity mimicking coral-algal interactions. Oxygen patterns were...
peerj.com
Biological oxygen demand optode analysis of coral reef-associated microbial communities exposed to algal exudates
Exposure to exudates derived from turf algae stimulated higher oxygen drawdown by the coral-associated bacteria.
Algae-derived dissolved organic matter has been hypothesized to induce mortality of reef building corals. One proposed killing mechanism is a zone of hypoxia created by rapidly growing microbes. To investigate this hypothesis, biological oxygen ...
www.ncbi.nlm.nih.gov
Microbial ecology: Algae feed a shift on coral reefs
Human pressures on coral reefs are giving macroalgae a competitive advantage over reef-building corals. These algae support larger, and potentially pathogenic, microbial populations that are metabolically primed for less-efficient, yet faster, carbohydrate remineralization, perpetuating a...
www.nature.com
Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages.
Increasing algal cover on tropical reefs worldwide may be maintained through feedbacks whereby algae outcompete coral by altering microbial activity. We hypothesized that algae and coral release compositionally distinct exudates that differentially alter bacterioplankton growth and community...
www.ncbi.nlm.nih.gov
Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching
Elevated ammonium delays the impairment of the coral-dinoflagellate symbiosis during labile carbon pollution
(here's an argument for maintaining heavy fish loads if you're carbon dosing)
Labile dissolved organic carbon (DOC) is a major pollutant in coastal marine environments affected by anthropogenic impacts, and may significantly con…
www.sciencedirect.com
Excess labile carbon promotes the expression of virulence factors in coral reef bacterioplankton
Coastal pollution and algal cover are increasing on many coral reefs, resulting in higher dissolved organic carbon (DOC) concentrations. High DOC concentrations strongly affect microbial activity in reef waters and select for copiotrophic, often potentially virulent microbial populations. High...
www.nature.com
Unseen players shape benthic competition on coral reefs.
Recent work has shown that hydrophilic and hydrophobic organic matter (OM) from algae disrupts the function of the coral holobiont and promotes the invasion of opportunistic pathogens, leading to coral morbidity and mortality. Here we refer to these dynamics as the (3)DAM [dissolved organic...
www.ncbi.nlm.nih.gov
Allelochemicals Produced by Brown Macroalgae of the Lobophora Genus Are Active against Coral Larvae and Associated Bacteria, Supporting Pathogenic Shifts to Vibrio Dominance.
Diverse microbial communities associate with coral tissues and mucus, providing important protective and nutritional services, but once disturbed, the microbial equilibrium may shift from a beneficial state to one that is detrimental or pathogenic. Macroalgae (e.g., seaweeds) can physically and...
www.ncbi.nlm.nih.gov
Macroalgae decrease growth and alter microbial community structure of the reef-building coral, Porites astreoides.
With the continued and unprecedented decline of coral reefs worldwide, evaluating the factors that contribute to coral demise is of critical importance. As coral cover declines, macroalgae are becoming more common on tropical reefs. Interactions between these macroalgae and corals may alter the...
www.ncbi.nlm.nih.gov
Macroalgal extracts induce bacterial assemblage shifts and sublethal tissue stress in Caribbean corals.
Benthic macroalgae can be abundant on present-day coral reefs, especially where rates of herbivory are low and/or dissolved nutrients are high. This study investigated the impact of macroalgal extracts on both coral-associated bacterial assemblages and sublethal stress response of corals. Crude...
www.ncbi.nlm.nih.gov
Biophysical and physiological processes causing oxygen loss from coral reefs.
Because sponges are essential players in the carbon, nitrogen and phosphorus cycle(s) on reefs here's some links to research done with them.
Element cycling on tropical coral reefs.
This is Jasper de Geoij's ground breaking research on reef sponge finding some species process labile DOC 1000X faster than bacterioplankton. (The introduction is in Dutch but the content is in English.)
Marine sponges are ubiquitous colonizers of shallow, clear-water environments in the oceans (1, 2). Sponges have emerged as significant mediators of biogeochemical fluxes in coastal zones by virtue of respiring organic matter and facilitating both the consumption and release of nutrients (3, 4)...
www.pnas.org
Phosphorus sequestration in the form of polyphosphate by microbial symbionts in marine sponges
Coral reefs are highly productive ecosystems that raise a conundrum called “Darwin’s paradox”: How can high production flourish in low-nutrient conditions? We show here that in three abundant Caribbean sponges, the granules that have been commonly observed in sponge tissue for decades are...
www.pnas.org
Differential recycling of coral and algal dissolved organic matter via the sponge loop.
Sponges treat DOC from algae differently than DOC from corals
Coral reefs are economically important ecosystems that have suffered unprecedented losses of corals in the recent past. Why have Caribbean reefs in particu
academic.oup.com
Surviving in a Marine Desert The Sponge Loop Retains Resources Within Coral Reefs
Dissolved organic carbon and nitrogen are quickly processed by sponges and released back into the reef food web in hours as carbon and nitrogen rich detritus.
PDF | On Jun 23, 2015, Jasper M de Goeij and others published 2013 deGoeij Science Sponge loop | Find, read and cite all the research you need on ResearchGate
www.researchgate.net
Natural Diet of Coral-Excavating Sponges Consists Mainly of Dissolved Organic Carbon (DOC)
Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. ...
www.ncbi.nlm.nih.gov
The Role of Marine Sponges in Carbon and Nitrogen Cycles of COral Reefs and Nearshore Environments.
Explore millions of resources from scholarly journals, books, newspapers, videos and more, on the ProQuest Platform.
search.proquest.com
And since we're discussing favorable and not so favorable bacteria here's a paper looking at how different corals and polyps are influencing the bacteria in the water column.
Aura-biomes are present in the water layer above coral reef benthic macro-organisms
As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in...
Thank you! The research on reefs and the roles of DOC and microbes in maintaining coral health is really fascintating. It is gratifying to see more and more aquarists aware of current research unfortunately some of the discussion on aquarists forums also highlights some of the dogma ingrained in reefs keeping. I'd love or see articles written by the researchers who are doing the research.
Three very famous methods - Triton (macroalgae refugium) and Zeovit / Tropic Marin (carbon for bacteria) rely on things, which according to my superficial understanding of these studies, may increase the mortality of corals.
On the other hand, both of them are the most efficient nutrient export methods known in reef tanks.
I am aware that it is much more complex than that and possibly some macroalgae can release harmful DOC, meanwhile other might now. The same goes with carbon dosing - there are so many ingredients used for that purpose and each alters the microbiome differently.
The question is - relying on your knowledge and all the readings you have made, what would you suggest as a safer method? Going towards a refugium-based system or rather carbon dosing to stimulate bacteria populations?
Three very famous methods - Triton (macroalgae refugium) and Zeovit / Tropic Marin (carbon for bacteria) rely on things, which according to my superficial understanding of these studies, may increase the mortality of corals.
On the other hand, both of them are the most efficient nutrient export methods known in reef tanks.
I am aware that it is much more complex than that and possibly some macroalgae can release harmful DOC, meanwhile other might now. The same goes with carbon dosing - there are so many ingredients used for that purpose and each alters the microbiome differently.
The question is - relying on your knowledge and all the readings you have made, what would you suggest as a safer method? Going towards a refugium-based system or rather carbon dosing to stimulate bacteria populations?
Well, why do you believe carbon dosing is the best way to remove nutrients? What research can you point to that shows those three methods (carbon dosing) actually are the most effecient methods? Certainly aquarists have dosed carbon and assumed it was beneficiual due to the better colors. But what is being overlooked (and an excellent example of one of the dogmas ingrained in the hobby) is the belief that brighter colors equates to healthy corals when in actuality flourescing and chromo proteins are made to deal with less than ideal environmental conditions or disease issues.
One obvious explanation why aquarists get away with carbon dosing is some of the cryptic sponges in out tanks can remove it 1000X faster than the bacterioplankton in our tanks and supposedly removed by skimmers. Unfortunately cryptic sponges have also been shown to prcess different types of DOC differently and we can't test for or identify chronic issues caused by these different shifts in microbiomes.
Considering it can take decades for some corals to reach sexual maturity and reproduce it seems to me keeping an animal a few years is like keeping a puppy or kitten a few months. In light of the environmental and legislative issues surrounding reefs and reef keeping I thhink we should be embracing current research on keeping corla healthy as long as possible in our systems and not striving for a tank of "eye candy".
What's seems to me is ignored is photosynthetic animals are pulling out nutrients. For example, looking at the distribution of PO4 most of the oceans are about .2 mg/l which drops at the surface and fluctuates with phytoplankton then drops even lower around reefs. AS far as various type of DOC work done subjecting corals to higher levels of their own DOC caused death due to the increase of microbes.
Since youe goal is to keep a tank full of anemones here's one of mine. There's three different clone lines, a brown that orriginates with a wild BAT purchased in '98, a teal w/ pink tips from a friends system I got in '07 or '08 and a rose from a freinds tank of '12 oe '13. FIltration is just an empty sump, no skimmer or reactors and dosing is baking soda added spradicly. Water chagnes are a bucket weekly. The system also has plate corals reprodcuing asexually (it takes a couple decades for one to become a mature female). Doing a water change and wipping the algae off the glass takes about 15 minutes weekly and there's about another 15 - 20 minutes monthly for other stuff (testing, removing mushrooms, siphoning sand occasionally, etc.). (Note the rose actually gets to full size.)
i mean its possible, if you have a lot of stuff like mushroom and kenya tree & zoa with the anenomes, a nice full spectrum light that lets everything grow, and just like a pair of clowns, there really wont be much nutrient issues. you could do a water change every month or two. just to keep trace nutrients levels good. you can also feed the anenomes which is super benefical.
My anenome only system requires the most testing and dosing for alk and No3 of all 3 of my systems and shows very quickly when things are out of whack.
Also a little bit of carbon won't do it. For a full mixed species anemone tank, you're going to want a Lot of carbon, changed out frequently.
Well, why do you believe carbon dosing is the best way to remove nutrients? What research can you point to that shows those three methods (carbon dosing) actually are the most effecient methods?
I do not recall naming it the most efficient method, but it surely works quickly and provides the expected result.
When I was less experienced, I used to have NO3 spikes above 50 and seeing my corals dying, newbie carbon dosing did the trick and allowed me to decrease it within 2-3 days to acceptable levels (although powerful skimming and aeration are vital). I know doing things slowly is advised, but that was an emergency.
I am also referring to videos like this - and Fauna Marin's method, which allegedly prevents the growth of harmful bacteria.
I need to admit that with substances like sugar, I had multiple issues, but more sophisticated options like propylene glycol turned to seem to be much safer and better in a more balanced export of NO3 and most importantly PO4.
With carbon dosing, my feeding could be virtually unlimited (at a reasonable spectrum), as whenever I reach amounts like 3-4 frozen food cubes a day, an increase of carbon intake managed to maintain nutrients in low ranges.
I haven't conducted any experiments with controls and comparisons of various methods at the same time, so I am not questioning their effectiveness. All I know is carbon dosing is simple, cheap, effective and can yield extra bacterioplankton for corals or even according to Lou Ekus, can help in the transportation of PO4 from the water column to corals' tissue.
What I don't know though is a long-term perspective and results, which are less obvious (like the potential accumulation of harmful DOC) or other problems. What's promising is the fact, that well-though carbon along with bacteria dosing has proven to be effective in treating dino spread in reef tanks.
. . . I haven't conducted any experiments with controls and comparisons of various methods at the same time, so I am not questioning their effectiveness. All I know is carbon dosing is simple, cheap, effective and can yield extra bacterioplankton for corals or even according to Lou Ekus, can help in the transportation of PO4 from the water column to corals' tissue.
What I don't know though is a long-term perspective and results, which are less obvious (like the potential accumulation of harmful DOC) or other problems. What's promising is the fact, that well-though carbon along with bacteria dosing has proven to be effective in treating dino spread in reef tanks.
Back in the 90's a popular weight loss product, Fen-Phen, worked wonders and had lots of adherents touting it's benefits, then people started dieing. I've seen some spectacular looking systems using labile DOC aka carbon dosing. But all the research shows it promotes unatural shifts in microbial populations either directly or in directly like what happens when sponges process it.
In refference to your origial question about not doing water changes, considering how little we know and maybe more importanlty how little we can test for the various kinds or types of DOC and associated shifts in animal microbiomes I don't see how reef systems and animals can be kept healthy without water changes.
