Belgian Anthias
Valuable Member
The skimmer is inseparably connected with and indispensable for the reef aquarium. The skimmer continuously removes DOC and TOC, purifies the water from (undesired) organic nutrients and building materials and prevents remineralization of organics (waste). The skimmer removes living biomass and proteins and prevents the formation of dyes that turn the water yellow.
It appears that after being skimmed off > + -70% of DOC and TOC must be remineralized, that + -60% of the bacteria present in the water column are left undisturbed. It was found that a skimmer in the reef aquarium removes very few proteins, almost none. Hence the name "skimmer" and not "protein skimmer". In addition, a skimmer is very selective. Can skimming put serious evolutionary pressure on the bacterial population present in the water column in favor of the non-skimmed strains? Some strains of bacteria can be skimmed, others not. Some scientists question the use of a skimmer mainly for the last reason.
In the modern reef aquarium, with a focus on keeping stony corals, the skimmer is often the only active filtering agent. Nitrification, denitrification, remineralization, is a passive event that takes place in the aquarium itself, taking into account the fact that sufficient water movement and gas exchange is ensured in the reef aquarium.
As manager of the reef aquarium, one has very little control over the event, except for what they add themselves and they have few options to intervene, not with regard to the degree of removal of nutrients, nor with regard to what is being removed and the quantity. Active management is very limited. And to do that correctly one should be able to know what is being deleted and what is not being deleted.
The skimmer is known to remove little or no inorganic substances present in the water column and nitrogen that it is mainly available in inorganic form. Notwithstanding that an unknown part of the inorganic nitrogen is constantly removed as nitrogen gas, via passive simultaneous nitrification and denitrification (remineralization), a large part of the nitrogen remains, part of which cannot be reused by photo-autotrophs and heterotrophs as the skimmer constantly removes essential substances needed to have all the nitrogen present absorbed by photo-autotrophs. Only in systems where the passive nitrogen export is in accordance with the active but not adjustable removal of building materials will the balance in the supply of building materials be maintained. In many cases, a surplus of nitrogen is created and then hopefully this will be in the form of safely stored nitrate nitrogen. It is also possible that passively more nitrogen is removed in relation to amounts of building material removed by the skimmer. In that case, nitrogen may become the limiting factor for growth.
Enrichment of reef environments with dissolved inorganic nutrients is considered a major threat to the survival of corals living in symbiosis with dinoflagellates (Symbiodinium sp.). However, we state that the direct negative effects on symbiosis are not necessarily caused by the nutrient enrichment itself, but by the phosphorus starvation of the algae symbionts that can be caused by disturbed nitrogen (N) to phosphorus (P) ratios. (RossetEnCo2017)
In order to correct a too high nitrogen supply or and a too low passive nitrogen export, sometimes caused by the proper functioning of the skimmer, it is necessary to proceed to active removal of excess nitrogen. Sometimes an algae filter or scrubber is used to remove nitrogen, nowadays it often is advised to dose organic carbon. However, both methods, based on the assimilation of nitrogen, phosphorus, and all other essential building materials in a natural ratio, do not correct the nutrient balance that is so important for corals. The latter method exports nutrients in proportion to the performance of the skimmer and what is effectively removed cannot be determined.
The nutritional balance can be restored by actively exporting the nitrogen surplus by denitrification, by transforming it into nitrogen gas, or by actively adding the removed building materials needed to restore the balance. The first is easy to implement, correct active nitrogen management through the use of a bio-filter is not that difficult in practice. The fact that one would consider the latter questions the use of the skimmer.
With regard to the health of corals, a low DOC level appears to be more important than the prevention of high nitrogen and phosphorus availability. The intention is to keep the DOC level low, which makes it possible for cohabiting communities, such as the coral with its holobiont, to control the availability of carbon within the community, this way controlling its nutrient supply.
What if no skimmer is used?
Ref:
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www.baharini.eu
www.baharini.eu
It appears that after being skimmed off > + -70% of DOC and TOC must be remineralized, that + -60% of the bacteria present in the water column are left undisturbed. It was found that a skimmer in the reef aquarium removes very few proteins, almost none. Hence the name "skimmer" and not "protein skimmer". In addition, a skimmer is very selective. Can skimming put serious evolutionary pressure on the bacterial population present in the water column in favor of the non-skimmed strains? Some strains of bacteria can be skimmed, others not. Some scientists question the use of a skimmer mainly for the last reason.
In the modern reef aquarium, with a focus on keeping stony corals, the skimmer is often the only active filtering agent. Nitrification, denitrification, remineralization, is a passive event that takes place in the aquarium itself, taking into account the fact that sufficient water movement and gas exchange is ensured in the reef aquarium.
As manager of the reef aquarium, one has very little control over the event, except for what they add themselves and they have few options to intervene, not with regard to the degree of removal of nutrients, nor with regard to what is being removed and the quantity. Active management is very limited. And to do that correctly one should be able to know what is being deleted and what is not being deleted.
The skimmer is known to remove little or no inorganic substances present in the water column and nitrogen that it is mainly available in inorganic form. Notwithstanding that an unknown part of the inorganic nitrogen is constantly removed as nitrogen gas, via passive simultaneous nitrification and denitrification (remineralization), a large part of the nitrogen remains, part of which cannot be reused by photo-autotrophs and heterotrophs as the skimmer constantly removes essential substances needed to have all the nitrogen present absorbed by photo-autotrophs. Only in systems where the passive nitrogen export is in accordance with the active but not adjustable removal of building materials will the balance in the supply of building materials be maintained. In many cases, a surplus of nitrogen is created and then hopefully this will be in the form of safely stored nitrate nitrogen. It is also possible that passively more nitrogen is removed in relation to amounts of building material removed by the skimmer. In that case, nitrogen may become the limiting factor for growth.
Enrichment of reef environments with dissolved inorganic nutrients is considered a major threat to the survival of corals living in symbiosis with dinoflagellates (Symbiodinium sp.). However, we state that the direct negative effects on symbiosis are not necessarily caused by the nutrient enrichment itself, but by the phosphorus starvation of the algae symbionts that can be caused by disturbed nitrogen (N) to phosphorus (P) ratios. (RossetEnCo2017)
In order to correct a too high nitrogen supply or and a too low passive nitrogen export, sometimes caused by the proper functioning of the skimmer, it is necessary to proceed to active removal of excess nitrogen. Sometimes an algae filter or scrubber is used to remove nitrogen, nowadays it often is advised to dose organic carbon. However, both methods, based on the assimilation of nitrogen, phosphorus, and all other essential building materials in a natural ratio, do not correct the nutrient balance that is so important for corals. The latter method exports nutrients in proportion to the performance of the skimmer and what is effectively removed cannot be determined.
The nutritional balance can be restored by actively exporting the nitrogen surplus by denitrification, by transforming it into nitrogen gas, or by actively adding the removed building materials needed to restore the balance. The first is easy to implement, correct active nitrogen management through the use of a bio-filter is not that difficult in practice. The fact that one would consider the latter questions the use of the skimmer.
With regard to the health of corals, a low DOC level appears to be more important than the prevention of high nitrogen and phosphorus availability. The intention is to keep the DOC level low, which makes it possible for cohabiting communities, such as the coral with its holobiont, to control the availability of carbon within the community, this way controlling its nutrient supply.
What if no skimmer is used?
Ref:
Further Studies on Protein Skimmer Performance
Department of Chemistry, The Pennsylvania State University, University Park, PA 16802. Many factors contribute to the 'value' of a skimmer to an aquarist, including quality of construction, size, footprint, noise level, ease of cleaning, energy efficiency of the pump, and of course, the ability...
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