OK, on my PC today, so this is easier to sort. This the magazine review from their website here:
Testlauf
The below is A la Chrome Translate from German to English:
The important plant nutrient carbon dioxide is supplied to the aquarium most economically in gaseous form. The CO2 must be dissolved in the aquarium water using suitable technology.
This is most effective in what are known as reactors, which are usually installed outside the basin. Here the gas is fed into a container in parallel or counter-current to the aquarium water.
This container is filled with a medium (plastic carrier, baffle plates) so that there is a strong turbulence of gas and water. This more or less completely dissolves the CO2. Such reactors are mostly used in larger aquariums.
When I got the CO2 reactors from Jörg Düren to test six months ago (two models with different hose connections), I was a bit skeptical at first, because the construction made of glued PVC parts did not allow a look inside, and the devices could be opened neither. All reactors that I know of can be disassembled for cleaning and are visible so that you can monitor their operation.
The Düren reactor consists of a cylindrical vessel with a hose connection piece placed in the middle at the top and bottom. There are versions for 12/16 and 16/22 millimeter hoses. The socket for connecting a 4/6 millimeter standard CO2 hose is attached to the side at the top and is equipped with a hose lock.
Because I really wanted to know how exactly the reactor works and how it differs from conventional models, I researched on the Internet. There I came across Düren's patent application, which describes the structure and mode of operation of the reactor.
Carbon dioxide and water enter the reactor from above (vertical installation is important). The water is deflected horizontally by a baffle plate, creating a horizontal ring vortex. The gas bubbles are broken up and largely dissolved through intensive contact with the water. The vortex also ensures that the gas that is not immediately dissolved remains in the upper part of the reactor (gas bubble) and is continuously mixed with fresh water. The H2O enriched with CO2 is guided downwards laterally through a grid and/or sponge system and exits there again via the outlet connection. Due to the design and arrangement of the baffle plate, central tube and grid-sponge system, the reactor is virtually self-regulating: the more gas that is fed in, the more carbon dioxide is released. With this model, Düren dissolved up to 5,000 CO2 bubbles per minute with a pump capacity of 500 liters per hour. That's a lot for such a small reactor (compared to other models with similar power).
Now, of course, I was curious to see whether the reactor would prove to be as good in practice as the description promised. My largest aquarium (200 x 60 x 60 centimetres, 720 liters) served as the test tank. Previously, a Dennerle Maxi pinball machine (for aquariums up to 600 liters) was responsible for dissolving the gas in the aquarium water. The flipper is only designed for tanks up to 600 liters, but I wasn't aiming for high CO2 concentrations, a basic supply of around ten milligrams per liter was enough for me. The number of bubbles required for this was 140 per minute (9 °KH). With this setting, I had the impression that the CO2 was almost completely dissolved: the bubbles rising in the pinball machine became visibly smaller, and only tiny bubbles made it to the top. A three-chamber biofilter is attached to one of the two short sides of the aquarium, which I operate with a pump capacity of 1,000 liters per hour. When I asked, Jörg Düren confirmed that the power for the reactor was OK, so I didn't have to work with a bypass. The device with a diameter of ten and a height (without socket) of 13 centimeters should be accommodated in the clear water chamber. Since space is unfortunately very limited here, the installation was tricky. The reactor is designed in such a way that the CO2 and water inlets must be from top to bottom (in cocurrent). Because the water in a biofilter is pumped from the bottom up, the installation was a bit cumbersome. The construction just barely fit into the filter chamber. To avoid the transmission of vibrations, I inserted pieces of filter mat as padding.
First I had to vent the reactor. To do this, I put the filter pump into operation, but the CO2 connection piece remained unoccupied. Only when all the air had escaped through the nozzle did I connect the CO2 hose. However, it is not a problem if some air remains in the reactor. Jörg Düren assured me that it will be held after a short time. As with any CO2 fertilization system, a non-return valve and a bubble counter must be installed between the gas cylinder (with pressure reducer and fine needle valve) and the reactor.
First, I kept the previous bubble count (140 per minute). After two hours, the plants showed clear signs of increased assimilation. Numerous oxygen bubbles formed on the underside of the leaves of my spotted water lily (Nymphaea micrantha "Spotted") and pearled upwards. The endurance test then confirmed that the dissolved CO2 concentration in the aquarium had already risen from ten to around 20 mg/l.
The next day the value was 40 mg/l (measurement via the pH value using an electrode and via the carbonate hardness) - high time to reduce the number of bubbles! It is currently set at about 55 bubbles per minute. With this I achieve a CO2 concentration of 20 mg/l, so the reactor dissolves the gas much more effectively than my previous pinball machine.
The reactor has now been in operation for six months. I haven't done any maintenance yet. Jörg Düren confirmed to me that cleaning or venting during his previous test phase (two years) was also not necessary and probably will not be in the future either. If you still want to clean, the materials used allow treatment with hot water and vinegar. Backwashing is also conceivable.
An acquaintance who runs a 2,500 liter aquarium previously used a large external reactor installed above the biofilter tank for the carbon dioxide input. After the installation of the Düren reactor, a lower CO2 consumption could also be determined here (the supply is regulated via the pH value). The tiresome changing of the bottles now has to be done much less frequently than before. I wanted to know from Jörg Düren whether he had a small reactor for my wall aquarium (90 x 20 x 25 centimetres). Here I was not happy with all the entry systems I have tried so far:
• Ceramic frits have an enormous back pressure and are very difficult to adjust. They always dosed either too much or too little CO2.
• With a suitable pinball machine, the bubble dwell time was practically zero (in Dennerle's mini pinball machine, the bubble takes less than a second to get from the bottom to the top
), so the entry is anything but efficient.
• Even a self-made diffuser (tube with a cigarette filter) was not optimal. Here the back pressure was negligible, but the dwell time of the generated gas bubbles was also very short due to the low height of the aquarium.
Unfortunately, Jörg Düren only had one large model. But because my inquiry kept him busy, he developed a small reactor that he let me test. I connected the six-by-eight-centimeter device to the outlet of my tubular reactor. Since then, the CO2 value has been easy to set and I'm happy with the much lower consumption! According to Düren, this new mini-reactor is suitable for aquariums up to 1,000 liters and releases up to 400 bubbles per minute.
In addition, Jörg Düren expanded his product line with another reactor ("Midi", 7.5 x 10.5 centimeters, for aquariums up to 3,000 liters, maximum 1,500 bubbles per minute).
In conclusion, the advantages of the Düren CO2 reactor can be summarized as follows: extremely high efficiency even with high bubble counts; low flow resistance; simple, maintenance-free and safe design; installable inside (biofilter) or outside the aquarium; cheap to buy.
Petra Fitz