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News & Reviews Article
| Title |
The EcoSystem Revisited |
| Author |
Mike Paletta
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| Last Updated |
2014-12-13
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| Abstract |
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The EcoSystem Revisited
by Mike Paletta - SeaScope, Fall 1998, Volume 15
I wrote an article for the Summer 1997 SeaScope discussing a new method of marine aquarium filtration called Ecosystem method, developed by Leng Sy. This article has spawned much debate. One author stated the system was theoretically impossible, even though he had not tried it. Other authors speculated about what was happening in the mud. I stated in the article that I would try out the system and report my own experience with it. I have pooled my results and those of other aquarists trying this method, and my report follows.
Before beginning the discussion, I should explain briefly the theory behind the system. It is a hybrid Jaubert system? algae filter. The key to its is a patented mud substrate that is on the bottom of a specially designed sump. Water flows from the tank overflow into the sump over bioballs that break down any ditritus, and then into a second larger chamber that contains a bed of Caulerpa algae that rests above the mud. A sieve-like separator keeps the Caulerpa from following the water back into the tank. The Ecosystem method uses no protein skimmer, chemical filtration, or trace element supplements. The only maintenance is a weekly 5% water exchange and calcium and buffer supplements. I now make 5% water exchanges in my system every two weeks with no lessening of water quality.
I set up my 90 gallon Ecosystem tank in August of 1997. Once I had saltwater in the tank and adjusted the plumbing and lighting, I added 20 pounds of Leng's mud to the sump. Water circulation was stopped for nine hours to allow the mud to settle in the sump. It is shipped in dry form and not washed before adding to an aquarium. After the circulation was restarted it ran for about a week before I added 100 pounds of fully cured Fiji live rock. I put it on a PVC skeleton for easier maintenance and to reduce the number of rock to rock interfaces. Detritus removal is easier this way. The removal of excess nutrients by siphon is crucial to the success of this system. I chose to use cured live rock because extra nutrients are released into the water as rock cures, and these may strain the capacity of the system. This seems to be the one obvious flaw in the Ecosystem method.
After one week with only rock in the tank I placed three cuttings of Caulerpa taxifolia in the sump. It is suggested that cuttings be weighted down with small pieces of live rock so the Caulerpa is in direct contact with the mud. After three weeks the Caulerpa had grown significantly and the rocks were removed. The species of Caulerpa used does not appear to be critical to success of the system. Other hobbyists have used Caulerpa racemosa, C.prolifera, and C mexicana. James Lawrence used a mixed bed of different species he collected from the Caribbean.
The water quality appeared to be good at this time, so I added sixteen coral heads and ten fish from another tank. All the corals extended their polyps within days or hours of addition. The animals appeared to thrive over the next two months, so I filled the remaining space on the rock structure with corals and mushroom rock, and added more fish and invertebrates.
After three months the fish and corals were thriving, the tank was full, and it was at least as successful as a typical Berlin system. One minor problem that developed was the stubborn growth of Derbesia hair algae. After struggling with it for nine months I realized that the flow rate through the sump was probably too slow. I replaced the Iwaki 20 pump with an Iwaki 40, and the Derbesia disappeared within a month. Another problem is that the Caulerpa in the sump will eventually grow to the surface and die, providing another opportunity for hair algae to grow. To prevent this the Caulerpa should be pushed down every day or some of it removed periodically. In spite of these small problems, this mature tank contains 24 fish, 34 coral heads, and numerous other invertebrates. I make biweekly 6 gallon water exchanges, weekly doses of calcium and buffer, and change the light bulbs every six months.
Common corals thrive in this tank, but so do other, more difficult-to-keep organisms. Blue and purple sponges started from small cuttings have grown without ever having been fed. The same is true of a Chili coral, Nephthytigorgia sp., that usually requires hand feeding. A Golden angel ( Centrophge aurantia) and a Mandarin fish (Synchiropus splendens) have survived more than nine months. This may not sound like a long time, but in my Berlin tanks they never lived more than three months. My pair of Percula clownfish spawn once a month. These successes may be the result of not using a protein skimmer, which removes plankton, a potential food. Although the mud is shipped dry, within three months it is teeming with worms, copepods, burrowing molluscs, and amphipods. These are probably food for animals that typically do not take commercially prepared food.
The theory that plankton is present in the tank is proved by an experiment I conducted over the past seven months. My Banggai cardinalfish produced offspring and I managed to rescue them from the sump of my 480 gallon tank. I had no free tank for them, so I put them in the sump of my Ecosystem tank. Over the last seven months they have grown from one centimeter in length to adult size, without ever having been fed directly. The only available food was whatever they could catch in the sump. I hope to transfer some of the clownfish larvae to the sump after one of the spawns to duplicate this success. If that trial works it would be simple to build larger sumps than are required in which fry could grow to a size large enough to take commercial food. I am also experimenting with a small add-on Ecosystem filter for my 480 gallon tank to see if the addition of plankton and trace elements from the mud will be beneficial to a tank with a protein skimmer.
I suggest regular water testing. In this tank, ammonia and nitrite are at undetectable levels, However, a recent test revealed a phosphate level of 0.78 mg/l, and a Nitrate/Nitrogen level of 2.5 mg/l/ In spite of these high levels the corals are thriving an nuisance algae is absent. Keep in mind that this tank has a heavy load of fish. These nutrient levels are far below what would be found in a year old traditional fish aquarium. The results also point out the need for periodic testing even if everything looks great. If you only test when there is a problem you will not know what the normal levels are.
Other testing reveals that the calcium level is 390 ppm and alkalinity is 3.6 dKh. Specific gravity is 1.023 and the temperature averages 77 degrees. Six 3 foot VHO fluorescent bulbs light the tank twelve hours a day. Polyp extension in all the corals is quite good and they have grown well. The only supplement I use is weekly addition of 30 grams of Tropic Marine Bio-Calcium.
There is a 1/2 inch layer of aragonite on the bottom of the tank. This does not make it difficult to remove detritus because the aragonite is only present in the front of the tank, not behind the live rock. I use only a thin layer because I have found that a thick layer lowers the oxygen level of the tank dramatically.
The Ecosystem method is probably also a good method for a fish-only system. Leng has designed a small above-tank filter for tanks 70 gallons or less. This system not only filters the water and produces plankton, but it also appears capable of reversing or preventing lateral line disease.
There are still as many questions today concerning this system as there were a year ago. As more hobbyists use this system many of these questions may be answered. As I continue to experiment with this system I will publish my findings. My next experiment will involve changing 1/3 of the mud annually. It has been proposed that the nutrients present in the mud will eventually be exhausted. I hope to compare two tanks, one where mud is changed and the other not. I am also planning to convert my 240 gallon soft coral tank to the Ecosystem method to observe the results. I would be interested to hear the experience of other hobbyists. I can be contacted through Aquarium Systems.
The ecosystem method provides an alternative to the Berlin method. Although I am still a strong advocate of the Berlin method, I must admit that there may be better ways to keep reef tanks. And despite conjecture to the contrary, I have no financial ties to Leng Sy or the Ecosystem Company, nor have I received any remuneration from them.
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