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SIMPLE CASE APPARATUS
CO 2 SUPPLY IN AQUARIUM

Vadim Lisovsky

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Glossary of terms

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DESIGN

The device consists of a pair of equal- sized PEF bottles ( green ), also a plastic tube ( orange ), along the diameter of the bottle entering the throat. The tube is closed with plastic stoppers on a pair of sides, the upper plug in the figure must ensure tightness. In the upper elements of the tube, not in any way included in the bottom bottle, there is a nipple for removing CO 2 ( black color ). Below it is also put on the cork from the bottle ( black color ), the tightness of this collapsible joint provides a rubber or silicone ring ( red color ). Under the cork made a spacious cutout for easy loading of chalk or limestone. Still further, the tube is perforated by a plurality of holes for free acid contact, also chalk. Through the top also the bottom stoppers the polyethylene tube for a cocktail ( blue color ) is punched. It is hermetically sealed also in the cork of the upper bottle - it is best to insert a plastic hollow rod inside its upper end, which securely jams the tube in the opening of the cork of the upper bottle. In order to neutralize acid vapors in the waste gas, it is bubbled through a solution of soda in a separate bottle.

SIMPLE CASE APPARATUS

OPERATING PRINCIPLE

The production of CO 2 is based on the well-known reaction between chalk and acetic acid. Chalk or limestone is needed in the form of pieces that do not pass through the opening of the tube, and especially there should not be any chalk dust. The device is poured with a weak solution of acetic acid almost to the top of the drop. shown in the figure. In the tube of the upper elements of the apparatus is placed pieces of chalk, it is inserted inside the bottle, and the release of carbon dioxide also begins. It is drained through the union, it breaks through a solution of soda and is also fed into the aquarium. On exit it is highly desirable to put a non-return valve. If the release of gas is not extremely violent - the apparatus works as if just a container with chalk is also acid. But if CO 2 is released more than necessary, or the CO 2 outlet is blocked (by a tap or valve), the evolved gas starts to force out the liquid from the lower bottle, and it also rises up the upper bottle along the central tubule. The reaction of gas evolution ceases, at what time the level of acid in the bottom bottle is made below the perforated chalk tube and also the basic capacity of the acid passes into the upper bottle. If the gas withdrawal is resumed, the pressure in the bottom bottle drops as well, the acid again starts to react with chalk. Thus, according to the principle of the Kipp apparatus, a constant gas pressure is maintained in certain limits. This pressure, respectively, the waste of gas, will also depend on the depth of immersion of the nebulizer in the aquarium.
It is not necessary to feed gas to the FAT suction port or a light ejector - the discharge at the outlet of the device can lead to acid entering the pool (it will foam also through the tube the gas-liquid emulsion will flow).

REAGENTS

The rapidity of the reaction depends strongly on the content of calcium carbonate in the used chalk or limestone, the density of the porosity of the mineral. I advise you to first choose the concentration of the acid on a small sample - the gas evolution should be sufficiently weak, unacceptably strong foaming as well as bubbling. If the slow course of the reaction does not provide the right amount of gas in any way, it is better to re-assemble the device by screwing the bottles of a larger capacity than using a more concentrated acid. On the other hand, a small concentration of acid can lead to the need to more often transfer the device - it will become extremely neutralized. In general, it will be necessary to select.

FOR WHAT IS IT ALL ABOUT

As I present, there are some benefits - CO 2 costs less than from brags also from cylinders - because the device itself is not worth it either, the reagents are cheap enough (limestone is general free). The device at the expense of its device allows you to stop the flow of CO 2 at night without any special risk - the gas is automatically cut off. Disadvantages - will have to work hard to reliably also hermetically assemble all of this, which is decently harder than withdrawing from a bottle with a brag. But you can also buy in the chemist's shop also finished such a device of glass Smile happy Just do not forget also the outer grid for it - such a device with hydrogen decently spread on my eyes also flying in all directions splinters of glass - in no way the most pleasant thing.

ATTENTION !!!

This unit is working under small pressure, but also with a weak but acid.
If you are not sure of the strength of the connections made by the elements of the device - put it entirely
in a large capacity or a strong leakproof plastic bag!

The author of the article: Vadim Lisovsky