I'm curious how reef fish relate to aquaponics though? Has anyone figured out how to manage salt water aquaponics?
I believe the concept would the same. Salt water aquariums use biological filters (live rock and others) and protein skimmers, along with water changes as needed. My immediate question is which edible plants will grow in salt water?
In my research I have come across a number of papers related to the chemical constituants of alquaculture sludge. These mostly entailed studies of tilapia RAS systems, and if you want to be more specific, only remains applicable if you use the same fish food. In general what it did show was that all basic growth elements required by plants, sans Molybdenum and Boron were present in the sludge, and that most of the elements were in a range suitable for plants, some a bit on the low side, some a bit on the high side. People also often forget that with fish, there are excretory pathways - solids and dissolved materials excreted through permeable membranes directly into the water. You therefore have to balance both sources of nutrients when looking at the usefulness of aquaponic solution for plants.
Eish! Seems like I have to clarify my stance a bit.
The ecosystems we create contains the following:
1) recycling pathways - VERY important. All the microbes in our system.
2) Primary producers - the plants. The problem is that typically, the consumers of this system is not "resident" but migratory - US.
3) consumers - the fish, and us. We are part of the system (but don't feel obliged to go live in the tank)
4) population dynamics - we sow seeds, transplant them, introduce fingerlings, grow them out, eat them, stick in new fingerlings. We can also breed our own stock. This is a modification of mortality and natality. We ensure that nothing important dies out in this system. If we do not go and buy them elsewhere, the loop remains closed.
5) Imports - the buffers, micro nutrients and fish food we add
6) Exports - everything we remove.
I was not referring to some form of biopod when I was talking about a closed loop, but the following scenario that, as far as I am concerned, provides a closed loop in production philosophy. See yourself as predation or consumption, because that is what you are. Mr bear or fish eagle does not fillet his fish and dump the wastes back into the river. It is a predation export, which we then balance out with the import of a fingerling in its place. Now, if you were responsible for the production of said fingerling, you are still operating in a closed loop. If you take the wastes from your system, and produce BSFL for your system, then you are still keeping the loop closed. If your greenhouse has gutters, and all the water you use drops from the sky, then the loop is still closed - no municipal input. If you grow duckweed as part of your system, and use it as food for the fish, the loop is still closed.
Thus, to get back to what I said before, my closed system:
I have a greenhouse with gutters that catches water. The water keeps my tank levels right. Solar and winds supplies the power. I harvest some seeds from production, and use them the next year (if possible). I grow my own fish, and produce their food (if possible) from components of the system. What you take, you take as the apex predator. I do not use clarifiers, and I do not pull solids from the system. I do not clean my gravel - the bits that stays behind after I pull the plant out breaks down again. In other words. If you have no municipal services, and do not buy anything from a store, can you keep your system functioning. THAT is the question I am working towards.