Almost completely self-contained ecosystem in a reef tank?

[mell0w]

If I were to grow macroalgae inside my display tank (chaeto, calurpa, some others maybe), had a smallish bioload (3-4 fish in a 55 gallon), kept my trace elements up with say SeaLab N.28 blocks, had tons of live rock and sand, a well established biofilter, clean-up crew, copepod population, what else would really be important? I know in nature wave-breaking occurs and exports proteins and other detritus on-shore, and there's really no other way to replicate that other than a protein skimmer no?

 

[xxkenny90xx]

What else is needed? Some flow and heat is all. What other equiptment could be added? The list is endless.

Fwiw I do really like having a protein skimmer and auto top off

 

[ichthyogeek]

I'm assuming that you're looking to mimic an ecosphere/biosphere/what have you with your tank, in that it's a "set and forget" system with no additions of food, or removals via water changes. You would have to add water to counter evaporation. You might also need to dose nutrients for the macros to take up as well, so the herbivores of the system could eat it, and in turn be consumed by omnivores/carnivores of the system (in this case, your fish). In this case, you may not want to use a protein skimmer, in order to keep element balance (N, P, K, etc.) within the tank.

You'd probably also want to mirror your fish to reflect this. Probably a surface film grazer like an Ecsenius blenny, a sand sifting small fish like a Valencienna or Signigobius, and a podivore like a possum wrasse. Perhaps a CUC eater like a puffer once the CUC snails started reproducing enough. The smaller the better, and the more likely you are to succeed. You would probably also need to figure out how to keep the macros in check, as the typical grazers (tangs) would get too big for the system to provide for it.

 

[ichthyogeek]

Overall, given the parameters, probably not implausible, but most likely very hard. It would make an interesting experiment at some point. I believe that it would be best if you could control for every thing in the tank. There are a number of anecdotes of dragonet species living only off of the pods produced in 180 gallon systems, so it's not improbably, but it would have to be approached carefully.

Start with bacteria in a bottle, since it's been controlled to have certain species. Also add in a number of "sludgivore" bacteria, which will break down detritus.Then go with a set number (let's just say 10) of "film algae" species, preferably high nutrition species that the chosen herbivore would eat. You could probably also use microalgal species like Nannochloropsis and Isochrysis as well, since those have a tendency to settle. Not many fish are small enough to graze on macros in a system that's only 55 gallons; perhaps in a 180 gallon aquarium, but not in a 55. Then go with 3-4 known copepod species. A number of sand sifting species that aren't polychaete worms as well. Amphipods and mysis shrimp, since they would serve as intermediates between eating copepods, and in turn being eaten by fish.

An ecsenius blenny to eat the film algae species + some of the copepods; perhaps two. A single Signigobius goby to sift through all of the sand in the system and keep detritus suspended long enough. A benthic podivorous fish that does not have a primitive digestive tract (i.e. no syngnathids), nor an ultra fast metabolism (no dragonets, no anthias).