Critical Mass - a self feeding tank

[Thallone]

I am trying to reach a critical mass of planktonic crittes, micro and mini inverts, suspended algae and other beneficial critters in my home aquarium. I have approximately <very approximate> 50 to 100 lb of live rock aquired over a 2 year period. This rock is stored in 2 tanks, about half is in the display tank, and the rest is in a second tank, that, when I get some lights replaced will be a refugium, but is more like a storage right now. Lighting is 380 watts or so VHO split 50/50 daylight actinic.

I have a Cup coral, several types of buttons, several well-covered mushroom rocks, a Toadstool leather, and several Carpet corals, a medium carpet anemonie, and a couple small clowns, one TR percula, one TR Clarks. There is a large clump of ogla? algae in the refuge, and there is a fair amount of red leaf- type algae in the display tank, growing by leaps and bounds.

For fish, I hope to add a small tang, preferably blue, to the tank, along with a Scooter dragonette, and a small wrasse, probably 6-line. Inverts and corals that I hope to add are, other soft corals, some hard corals, including closed brain, and sps including hardier TR Acroporas.

I hope to feed the tank and the critters in it as little as possible, and to produce the majority of the feeding from the critical mass of plankton and other foods coming off of the LR, including micro-inverts such as mysids and copepods, amphipods, etc. I also plan to add a surge device to this tank, as soon as my ambition grows a bit more.

So, the question is, what else do I do to get the tank to the critical mass of the critters I describe? What else do I need to consider doing?

[TroyF]

Hi Thallone,

I think that you are looking at a sort of catch 22. In order to maximize the life in your tank you have to feed the tank. In a closed system I don't see how you can keep it self sustaining.

Depending on the size of tank, it won't take long for the tang to eliminate natural food sources and again depending on the size of tank the same goes for the scooter blenny. I haven't witnessed my clown being much of a forager though he takes the odd peck at the rocks.

As for your corals there is much debate as to whether to feed or not. A couple of months ago there was quite a debate going on between Richard Harker and Rob Toonen and Ron Shimek in regards to the need to feed. I think it either took place on the reefkeepers mailing list or on reefs.org. It was very interesting. If it was on reefs.org it will have been archived but I'm not sure about reefkeepers mailing list.

Troy

[Thallone]

Sadly, I have been self-sustaining before, but I did some experimenting to try to get the sps and other stonies I had at the time to grow better in a minimum maintainance system, and had a disaster that killed even the little red worms that are always in the sand.

At the time I had about as much rock as I could get in the tanks without overcrowding, and the tank was swarming with copepods, amphipods, and various other critters. For plants I had a caulerpa (sp) prolifera farm in the sand on one end that the tank could not eat fast enough to prevent my needing to weed occasionally, in addition to things on various other rocks. In addition to the tank, I had a clown, a bi-color blennie, a scooter, a mis-matched pair of damsels and several hard and soft corals.

The disaster's only survivors were a few of the mushroom polyps, a few of the buttons, and some of the purple coraline. What I find frustrating is knowing I CAN return to this state, but other than buying prohibitive quantities of live rock that I don't have a place for, I havn't a clue how to get there.

The system that I'm running right now is very healthy, but it is way too low on the micro-inverts and mini-inverts that are the food of the larger things I have in the tank.

I hope this additional information helps.

thanks for any information you can provide all!

[This message has been edited by Thallone (edited 01-24-2001).]

[Markv]

What you are trying to do is impossible. In reef tanks, localized extinction of various microfauna occurs over time. This is due to competition and overpredation. The overpredation issue is a big one. Carnivores like gobies and wrasses usually "hunt" on a large reef. They will feed on zooplankton in one location and then move onto the next. In the meantime, the previous location is allowed to recover through reproduction and recruitment from neighboring habitats. Same goes for grazing tangs. They forage over a reef, and never stay in the same place for long. With predation and grazing distributed over such a large area, the amount received by a small area of the reef is reduced. In your tank, the tang only has a small area to graze, and will completely decimate it's foodsource. Furthermore, recruitment is not available and the growth of the macroalgae will not keep up. Gobies like mandarins experience the same problem. A refugium helps, by offering a source for recruitment. But the refugium will have to be very very large to replace food input by the aquarist. Second thing to consider is that the refugium is also under selective pressures. As competition for space and food occurs, your variety of detritivores and zooplankton will drop drastically. Soon your refugium will not offer much in the way of recruitment. There are things you can do to get close to self-sustainment. One is to make your refugium larger than your main tank. Two is to grow a variety of macroalgae, and then feed your weekly harvest to your tang. By growing the algae in the refugium, you isolate it from overgrazing by your tang. Most importantly, I would replace a couple of pieces of live rock with fresh (but cured) live rock twice a year. This will introduce those organisms that have become extinct in your tank (A sort of manual immigration or recolonization). Doing these things is a good way to help sustain your reef's food webs. But it will never substitute feeding.

Matter cannot be created nor destroyed. So as matter exits your tank (caulerpa harvesting, sand bed converting waste into nitrogen gas, protein skimming), some matter needs to be put into the system to replace it. Otherwise the cycle will eventually stop.

I hope you don't mind all the ecosystem biology I'm spouting out. I got my degree in it so it fascinates me. I guess I can appreciate your goal, and so I figured you'd like to know the semantics behind it. If you want to look at your reef tank in a whole new light, check out some books on Island Biology. Island Biology looks at the way isolated environments interact and evolve. If you think about it, your reef is an isolated island. So many rules apply. The macroalgae that shows up on live rock that you introduce is very much like the log with plant life that drifts ashore and seeds a barren volcanic island.

And remember, there is no spoon.
Ok, I'll shut up now.


[This message has been edited by Markv (edited 01-25-2001).]

I was going to say that a much larger refugium than the display tank would help.
I would be leery of infauna predators such as the scooter dragonette( same feeding habits as the mandarins) and a sixline wrasse, a highly efficient predator of pods and other sand bed fauna such as terrebelids and juvenile snails. The wrasse will win out in the long run in competion with the scooter as its a more agressive feeder.

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I thought I was me, but we were wrong
email: geeflipr@internetcds.com

[tdwyatt]

Dr Walter Addy in the book "Dynamic Aquaria-- Building Living Ecosystems" addresses this issue in Chapter two, and much of the information presented there will answer a few of your questions. Yes, it is possible to build what could be considered a self-sustaining microcosm, if you take into account the need for solar energy input and a water cycle associated with a self renewing source, but Dr addy's comments on this type of system are based on a minimum size of around 500,000 gal up based on the inhabitants of such a system. Population dynamics account for much of the variability, as do many other setup factors. The longer the food chain, the larger the system needs to be. Prolly too complex an issue to follow in a threaded bbs discussion, but it is an interesting topic to research. I will try to find the island ecology info above, check Dr Addy's book (gets into why some of the things we do in our microcosms work...)

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Tom <"{{{{>(
(TDWyatt)
Wise men talk because they have something to say; fools, because they have to say something. -Plato

[This message has been edited by tdwyatt (edited 01-25-2001).]

[Thallone]

Thanks for all the input, all.

I guess I should say that I intend to occasionally feed, just that I don't want to have to, especially for the corals. The fish, currently 2 clowns, are doing quite well fending for themselves. I think I may have fed once this month.... The trick will be to recover the fauna to the point where larger poulations do well, and the corals thrive.

Does anyine know if it would be safe to use the proliferation of small tube-worms to assess the amount of plankton-like feed availabe to the tank? Or do these worms filter out micro-algae?

Again, thanks for all the advice and help.

[bmw]

You might look at the 1st and 2nd laws of thermodynamics. Even with a 500,000 gal system.

b.

tagged for archives

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I thought I was me, but we were wrong
email: geeflipr@internetcds.com

[TroyF]

Where's Horge, this thread begs for his input.

Good question, I havent heard from him for a few days,, lat i heard there was some political upheaval in the PI, but I dont watch the news

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I thought I was me, but we were wrong
email: geeflipr@internetcds.com

[Markv]

The fanworms are one good indicator. I would also focus on the diversity of your critters as an indicator. Not only look for fanworms, but look for a proliferation of spaghetti worms, small crustaceans, etc. Be aware that phytoplankton (which could be considered the start of your food web) is usually not common in a reef tank at large quantities. This might be something you have to add, which would then feed one organism that feeds another, that feeds another, which eventually provides a food source for your clowns.

[Wrasse Man]

I think it was either a rebellion or a coup, my NPR doesn't come in clear the whole way into work, so don't hold me to that.
I am sure about demonstrations though.

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"Nothing good ever happens fast in a reef tank."

[Doug1]

Once more to the top, Horge anyinput before archiving?

[Doug1]

Horge, care to add to this before it goes into archives?
Jerel, Chris, anyone??????????