Self-Sustaining Tank Project

[mackwilson]

Ok, so im starting a rather difficult project for a school assignment. I want to do something that will take some time. My idea was to create a self-sustaining ecosystem with a 155 gallon saltwater tank. I have a tank set up and it has been a predator tank for about 2 years now, but i want to switch it to a reef tank. The idea is to have something that doesnt need water changes of food or anything, a completely self sufficient, scaled down version of the ocean. Im aware of the difficulty and i havent found anyone who has pulled it off, but it would great if someone could give me some advice or some resources to check out. I plan on logging all the involved bacteria and plant life that will go into the recycling of the water, and hopefully will be able to add a few small fish if everything goes well. i was thinking about adding a refugium, or something to have an extra biological filter. I could settle for doing water changes maybe once or twice a year, but i really want something completely independent. any advice would be great, im having trouble finding it on the internet.

[skinz78]

IMO you won't find any info on this because I beleave that it is impossible to do.

1. you won't have a sufficent food source.

2. you will have evaporation which requires maintainance "not self sufficent"

3. over time you will see the effects of old tank syndrome Advanced Aquarist's Online Magazine - Feature Article: The "Old Tank" Syndrome

4. your sand bed will need replentishing or it will go hard and die
Substrate is hardening

Those are some of the many reasons why I don't think it would work out for you. Sure there are ways to make it low maintainance but 100% self sufficent, no way.

[charlesr1958]

I for one want you to try as I am about to embark on such a mission, although it will not be completely self-sufficient as there will be some supplementation that will need to be done. But... with multiple aquariums that share the same water, you can get a lot closer than you would imagine. It just takes some understanding of the various habitats, their species compositions and such and to have the various habitats in somewhat of a proper proportion to each other. An example would be a macroalgae reef flat vastly larger than a coral dominated fringing reef. Which is why my 80 gal tank is going to become the "refugium" with what used to be a 20 gal refugium becoming a Pocillopora dominated coral display tank.
Anyways, you might find these articles of use:

A Philippine Fringing Reef and the Reef Aquarium - Part One (contains links to parts 2-4)

Chuck

[mackwilson]

Im aware of the difficulty, which is what intrigues me. I might not be able to get to 100% self sufficiency, but as close as possible would be nice. Just understanding the bacteria and various animals involved in the cycling would be great. In theory its possible, its just getting there. I dont plan on putting thousands of dollars into this for corals and fancy reef animals, the goal isnt for beauty, but an experiment.

[tholleyh46]

If your intent is just to eliminate water changes - you can do it easily. There are several people who do this already, and if you don't have sensitive inverts or corals - things may suffer but will most likely survive.

You can use the berlin method with no skimmer, and add a refugium - grow mangroves - whatever. Without a skimmer pretty much all you'll need to do is top off the evaporation and clean the tank - if you don't clean it the walls of the tank will become sheets of algae though. I don't really understand what you're trying to accomplish; but you'll find several people who try to apply a more 'natural' reef without using all the gadgets and gizmos. Read up on Lee Chin Eng, and how his efforts led to advances in modern reefkeeping. His methods were very basic. Some folks swear by mangroves, and while I've tried them - I've never abandoned the idea of using a skimmer although I know some who have.

Good luck.

[Ninong]

Hi Mack,




Others have tried something similar to what you are proposing but with certain modifications. For starters, as Charles1958, has already mentioned, it usually involves multiple, separate tanks that are interconnected.

There would be a main display aquarium that would be lightly stocked with corals and a few fish. There would be a large refugium -- usually larger than the display aquarium -- and a third tank to house macroalgae, such as Chaetomorpha, that can be harvested regularly to export nutrients (pollutants) from the system.

This is usually only attempted on a rather large scale. The display aquarium might be only 150-180 gallons but the refugium might be a 300-gallon Rubbermaid stock tank and the tank housing the macroalgae might be at least 50 gallons.

Both the display aquarium and the much larger refugium would have deep sand beds (4"-6") loaded with infauna. The display aquarium would be lit for 12 hrs per day and the refugium would be lit the 12 hours that the display aquarium is dark. The tank housing the macroalgae could be lit for 20 hrs/day. It does not have to have a sand bed. Caulerpa should be avoided because of the potential to go sexual and because of the toxins produced by Caulerpa. The chaeto can be harvested twice a month.

I know of someone who tried this exact set-up several years ago except that I believe his display aquarium was larger than 180 gallons. In general, it would be better if the refugium were more than double the size of the display aquarium. He set up a Rubbermaid stock tank and filled it with about an 8" deep sand bed. He then added some live rock and live rock rubble to this refugium. He also added several mangrove trees (grown from pods) but the mangroves are more for appearance than they are for nutrient export. I still think they looked nice. This refugium was set on a raised platform in his equipment room behind the main display tank, which was a built-in-the-wall tank. The equipment room had a large window and a skylight, so it was impossible for him to have its daily photoperiod exactly opposite that of the main aquarium except that he had his main aquarium's lights set to run from 11 a.m. to 11 p.m. so that he could enjoy it when he was home from work.

His main purpose -- at least his stated objective -- was to run a system without a protein skimmer. He had snails, hermit crabs, polychaetes, sand cukes, etc. in the display aquarium but no hermits in the refugium. The refugium had snails and polychaetes and sand cukes but no predators (hermits) that might eat the beneficial sand bed infauna. Both the display aquarium and the refugium had thriving populations of amphipods and copepods. I believe he added live mysis shrimp to the refugium but I don't know if he was able to keep that population going.

Theoretically at least, such a system should be able to operate for a year without a water change provided you monitor calcium, alkalinity and magnesium and supplement as necessary. You can set up an automatic water top-off system to keep up with evaporation.

I believe his main tank was at least 300 gallons but I really don't remember for sure. This was about eight years ago and he took down his website a couple of years after he started this project. His 300-gal refugium was set on a wooden platform that he built. The refugium overflowed into his sump. Ideally the refugium should overflow into the main aquarium but that requires that the refugium be situated higher than the display aquarium, not an easy feat for a very large refugium.

The plan there is that the natural zooplankton produced by the deep sand beds would be sufficient to keep a few small fish thriving. That and the amphipods and copepods that inhabit the live rock. You don't want such a system to operate too clean (meaning very low nitrates) or you wouldn't have any algae in the main display tank to feed any herbivorous fish.

It would be very difficult to have such a system totally self-sufficient without any food additions but it might be possible if the size of the system is large enough and the bioload in the display aquarium small enough. In other words, a 500-gal refugium on a 100-gal display aquarium would have a better shot than a 100-gal refugium on a 500-gal aquarium. And the more chaeto harvested the better.

Similar systems have been set up in public aquaria (especially in Europe) but they cheat in that they're usually open systems -- that means they get nightly inflow of natural seawater from the actual sea. This refreshes their natural water parameters, as well as providing natural plankton.



P.S. -- One final word. Your idea that an aquarium is in reality an ecosystem is absolutely valid. Your goal is to establish natural food webs and self-sustaining populations of microfauna, epifauna, infauna, bacterioplankton, etc. to nourish the larger life in the system. This is the goal of every reefkeeper, except that most reefkeepers accept that they will have to help things along more or less. Often more.

It will take a minimum of 18 months to establish mature sand bed systems in the display aquarium and the refugium. That's about the minimum time required to establish diverse, sustainable populations of sand bed infauna.

[Doodaa]

Mackwilson,

Did you get scared off of this project? If you didn't, I for one, and I'm sure everyone else, would love to see you document it. If nothing else, the end result, but if you did it as an "in process" thing, we could all spout off our suggestions

[mackwilson]

No, im definitely still interested. It may be difficult to reach full self sustaining, but im trying to get as close as i can get. I am planning on documenting the whole thing. Any one have any ideas on methods for documentation? i am recording every water test i do, recording weekly observations, keeping a log of what organisms i put in and take out. What other information might you think important? This whole project is for a school project, i wanted to do something that hasnt been done very often, im willing to spend a lot of time and energy on it.

[Ninong]

Any one have any ideas on methods for documentation? i am recording every water test i do, recording weekly observations, keeping a log of what organisms i put in and take out.

You can keep track of all of that information automatically by setting up your own log here: Personal Online Aquarium Log.

It's completely free.