julho 14, 2011

Aeração com CO2, senta que lá vem história.


Para comemorar os 7 anos de Xylema, completados em maio de 2011, resolvi postar algo que é mais que uma curiosidade, é história pura. Espero que apreciem, pois essa foi recuperada do fundo do meu baú digital e quase se perdeu (de novo).

Setembro, 1962. Chegam as lojas de revistas dos EUA o exemplar mensal da Tropical Fish Hobbyest (sim, aquela TFH mesmo que você pensou!), cujo maior destaque da capa eram as fotos coloridas que ilustravam seu conteúdo, um pequeno luxo para época digamos assim. Dentro daquela edição havia um artigo muito interessante descrevendo a experiência dos escandinavos com a injeção de CO2 em seus aquários e os benefícios para as plantas aquáticas, uma novidade até para os aquaristas americanos aquela época. Eu não tenho certeza alguma para afirmar, mas acredito que a injeção de CO2 só deve ter chegado ao Brasil uns 15 anos depois.

A história de como este artigo apareceu de novo depois de mais de três décadas também é interessante. Quem encontrou a revista, ou melhor dizendo, a dúzia de edições da TFH dos anos de 1960 a 1963 foi o webmaster do site Cryptocoryne.com, ele chamava-se Bill e por volta de 2003 postou sua história no site, se lembro bem devo ter lido o artigo por volta de 2003 na página do Bill e cheguei até ele pesquisando sobre Cryptocorynes, uma das plantas preferidas do Bill como vocês já devem imaginar. As revistas foram compradas em uma loja de usados em Allen, Michigan, e custaram $ 1 cada uma. Uma pechincha! As revistas continham etiquetas com o nome do Sr. Torrance de Altoona, Pennsylvania, dono original das edições. Temos muito a agradecer ao Bill e ao Sr Torrance por esse momento singular da história do aquarismo não ter ido para o lixo.

Posto a transcrição do texto em inglês, logo em seguida os scans das páginas do artigo e a capa da revista original:

Aeration with Carbon Dioxide - Tropical Fish Hobbyest - September 1962
The authors claim that plants, which need carbon dioxide to prosper, are greatly benefited when carbon dioxide is pumped into the water. Photo by Van Raam.

BY SVEND A. OBESEN AND BENT HANSEN, The Aquarium Club of Copenhagen, Denmark.

Today, many Danish aquarists have replaced aeration by air with aeration by carbon dioxide. Higher plant life in tanks aerated by bubbles of carbon dioxide seems to do very well, and the new method has proved instrumental in cutting down on the "melting" of plant leaves, especially in Cryptocorynes. Also (no doubt as a consequence of its aid in stimulating desired plant growth) carbon dioxide aeration helps to eliminate algae.

The value of using carbon dioxide in the aquarium is based on the plants' capacity for assimilating, under the influence of good lighting, the carbon dioxide in a body of water and turning it into organic plant substances. For our purposes we considered 12 hours of lighting per day to be sufficient, the wattage to be used depending on the size of the tank. Although the method has not been under study long enough to allow any positive statements regarding the total effect of carbon dioxide aeration on a fish tank over an extended period, we have been gratified by the results obtained so far. The plant physiology department of the University of Copenhagen is interested in the experiments, and it is believed that there is every likelihood that the new method will be a valuable contribution to the hobby. For the benefit of TFH readers who would like to try the new method for themselves, we are outlining below the equipment needed for the experiment, plus a few do's and dont's for general guidance in application.

A mixture of yeast, sugar, and water (one level teaspoonful of yeast, 31 ounces of sugar, 1 quart of water) is placed into a 2-quart glass bottle equipped with a one-hole rubber stopper through which a glass tube has been inserted. A length of plastic tubing is used, one end attached to the protruding end of the glass tube, the other end attached to an airstone. Fermentation will have begun between 12 and 24 hours after the mixture has been placed into the bottle, and the carbon dioxide, under pressure, will be forced from the bottle through the tubing and into the tank into which the airstone has been placed. Temperature plays a large part in the speed at which the process is accomplished; at lower temperatures the gas will be produced slowly, but at higher temperatures production will be very rapid. Since the method, to be of any value, should go at a slow but regular pace, it is best to keep the temperature down. 77¡F. provides a good steady flow. First experiments with the system used hydrochloric acid and marble as the source of gas production, but this gave off too much gas too quickly, and was therefore unsuitable. The yeast-sugar-water combination is much better; if set up properly, a single mixture should run a stone day and night for a full month.

General recommendations for the experiment:

DO watch the tank carefully, especially during the first few days. If the fishes show the least discomfort, stop the process.

DO use a large tank; very small tanks are unsuitable, because the fluctuations in the chemical makeup of the water could be too severe.

DO use strong lighting. Without strong light, the plants will be unable to assimilate the carbon dioxide no matter how much is in the tank.

DON'T choose as a test tank an aquarium which is crowded or near the crowded point. The animal life in such a tank will have already provided plenty of CO2, and more could be disastrous.

DON'T, DON'T, DON'T shake the bottle containing the yeast-sugarwater mixture.

We here in Denmark like to plant our tanks very densely. Perhaps this is because our far northern location creates in us an appreciation for things exotic and tropical, or perhaps it is simply because we feel that plants are just as much a part of the hobby as fishes. Anyway, we like our plants and are constantly on the lookout for things that will help them to grow better. If the carbon dioxide aeration system proves to be of real and lasting value, we'll be grateful for its welcome advancement of the hobby. For our part, we are going to keep experimenting, and we hope that hobbyists elsewhere will do likewise.

EDITOR'S NOTE: One thing that worried us when we first read this article was, wouldn't the fermentation in the bottle containing the yeast-sugar-water combination make the room smell like a brewery ? We asked Mr. Olesen about it, and he assures us that this is not the case.

Clique nas imagens para ver em tamanho original.




1 Comentários:

Luca Galarraga disse...

Fantástico achado Alex!
E pensar que os dinamarqueses já faziam garrafada há 50 anos atrás!

Parabéns!

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