Cryptic, Macro, or both?

[Nano sapiens]

Definition of OLIGOTROPHIC (Merriam-Webster)

: having a deficiency of plant nutrients that is usually accompanied by an abundance of dissolved oxygen <clear oligotrophic lakes>

In relation to the coral reef, oligotrophic best describes the water characteristics and not necessarily the individual organism:

http://www.nature.com/scitable/knowledge/library/coral-reefs-15786954

'In the warm oligotrophic waters where corals thrive, the nutrition provided by zooxanthellae supplies the needed energy for corals to secrete layers of calcium carbonate. Even with the nutrition provided by zooxanthallae, the process of building a reef is slow.'

True, individual organisms such as Acropora coral often have high metabolisms due to efficient utilization of the available nutrient sources.

 

[GroktheCube]

Generally speaking, the trophic state index is primarily used for closed, freshwater bodies. Trying to measure the trophic state of a coral reef by dissolved inorganic N and P paints an incomplete picture. Unlike a classical oligotrophic system, coral reefs have remarkably high primary productive, incredible biodiversity, and high density of biomass.

If you were to compare a given cubic meter of a reef to a given cubic meter of our tanks, or even a given cubic meter of water vs a given cubic meter of water, the total biomass and level of organically bound nutrients available to corals would be dramatically higher. There is a ton of N, P, and C available for corals, its just that the majority isn't floating around as NO3 and PO4.

This is why I disagree with the notion that things like refugiums or ATSes that convert inorganic waste into organically bound nutrients that can be harvested or utilized as food are counter productive for the keeping of corals. Describing the creation of biomass as eutrophication (in a negative light) is also not correct in my view. If levels of toxic dissolved inorganic nutrients are not substantially increasing along with DO and biodiversity not substantially decreasing, the process is not akin to what happens to a pond having fertilizer dumped into it.

My point isn't to nitpick over definitions, but rather to make sure that definitions are not used in such a way to suggest that accumulation of biomass is a bad thing.

 

[Nano sapiens]

My point isn't to nitpick over definitions, but rather to make sure that definitions are not used in such a way to suggest that accumulation of biomass is a bad thing.

Increasing biomass is a natural condition and would be expected on a typical healthy coral reef. However, there are natural processes (typhoons, mostly) that slow, halt or decrease this situation at any one time which tend to act as a counter-balance to unrestricted growth.

In a captive environment with continuous food inputs and very little if any restrictions on growth I believe that we, as aquarists, can maintain a safe, healthy system by setting a limit on how much bio-mass we allow in relation to the water volume.

 

[GroktheCube]

That makes perfect sense to me.

 

[Reefin' Dude]

i think the problem is that we are not understanding what nutrient limiting means when we talk about oligotrophic. it is that there is not enough inorganic available nutrients to support a thriving population of bacteria/algae. there can be a ton of organically bound nutrients in plankton/other multicellular organisms, but these organically bound nutrients are not available to algae/bacteria. the bottom rung of the food chain is limited in its food source.

G~

 

[muttley000]

What a great debate/conversation I am happy I have been able to read, thank you all! In all of this I have a question, where is more information about the settling tanks? I have a feeling that the OP is quite a lot like me and not wanting to put all of his filtering eggs in one basket. I too plan a system with a skimmer, ATS, Cryptic Fuge, Lighted Fuge, Mangrove fuge, and who knows what else down the road one day, however none of them will be able to single handedly support the system. I think that a settleing tank could be a simple and valuable part of a system like I have planned, and it doesn't appear to use any electricity! I have read some arguments that give me concerns with my plan, but I am glad to have heard them explained completely and with passion!

 

[Nano sapiens]

I too plan a system with a skimmer, ATS, Cryptic Fuge, Lighted Fuge, Mangrove fuge, and who knows what else down the road one day, however none of them will be able to single handedly support the system.

Some 'food for thought':

In truth, the 'filtration' needed to support a reef tank can be surprisingly uncomplicated. Basically, sufficient LR (or LR + LS) and some mechanism to create sufficient flow. These 'natural' type tanks (which is what I have used successfully for decades) can be very stable and provide excellent water quality when proper husbandry techniques are used.

All the filtration systems that you mentioned can be utilized, but the question to ask is which ones are actually necessary to perform a desired/needed function(s) that you are anticipating? I understand the desire for redundancy and a sense of stability, but consider that having many different filtration systems running simultaneously adds potential failure points to the system.

 

[Reefin' Dude]

on another forum there are several people that have incorporated conical settling tanks like this one (this one is mine, i was not able to incorporate it into my system before i had to take the system down because of a divorce).

most have the drains from the display going into the lower section of the cone with a nozzle point to the side to get a circular slow in the bottom of the tank. a flow break (a piece of eggcrate across the entire tank) is located higher up in the tank, but below the drain for the tank. the drain for the tank is located as high as possible and centered in the tank. the problem that some are having is that the HDPE that the tanks are made out of is not super slippery, so a quick wipe of the cone area is sometimes necessary to get all of the detritus down into the bottom of the cone.

flow through the settling tank is important. it should be the slowest amount of flow in the system. easily accomplished in BB systems, but can be a bit more difficult in oolitic based systems. matching the flow through the sump to the processing rate of the skimmer is also recommended to keep the flow as slow as possible through the settling and and makes for the best chance of all water leaving the system to be filtered by either the settling tank and the skimmer.

these settling tanks come in various sizes. bio-diesel and brewery supply places carry them. there are some rectangular ones out there also for fitting better into stands. some have thought about incorporating a cone bottom to the main sump, but getting the flow to not bypass the skimmer without creating a secondary settling area has not been eliminated.

G~