In the first part of the series “ The story of liquid CO2 fertilisation ” we look at the active substance of the products considered liquid CO2.
Carbon dioxide is the nutritional basis for aquatic plants which is supplemented through micro and macronutrients and light. The balance between all these elements is necessary for thriving plant growth in the aquarium. You will find further details in the post: Why is carbon dioxide (CO2) the most important plant nutrient in the aquarium?
Do products, which are advertised as “liquid carbon dioxide“, contain carbon or carbon dioxide?
No, since carbon is a solid (anthracite, diamond) at average ambient conditions (20 °C, 1 bar atmospheric pressure), whereas carbon dioxide is a gas which is only present in liquid form in pressurised gas cylinders (50 bar) under these conditions. Thus the products in these advertisements can neither contain carbon as an element nor carbon dioxide in liquid form.
But what do these products, advertised as „liquid carbon” for the aquarium, contain?
A simple test with one of these products shows that the active substance contained is glutaraldehyde (abbrev. glutaral) in a concentration of about 4 % as shown in the photo. After that we tested other products and found that the most common glutaraldehyde concentrations range from 1% to 4 %.
What is “glutaraldehyde“?
Glutaraldehyde is a disinfectant and is used industrially for various purposes, including in medicine, for example in dental practices. Glutaraldehyde is a dangerous substance in the aforementioned concentrations, and needs to be marked in accordance with EU directives.
For more details about its use we would like to refer you to Wikipedia: https://de.wikipedia.org/wiki/Glutaraldehyd
- • For the disinfection of medical equipment
- • Water treatment for industrial use, e. g. in fracking
- • For the disinfection of industrial facilities
- • In cleaning agents for surface disinfection
- • As a preservative
- • For tanning leather
- • For fixating tissue samples in microscopy
- • For the crosslinking of proteins. The aim is to increase the mechanical and thermal stability and to reduce self-decomposition
- • As plant fertiliser in aquariums
The use of glutaraldehyde for the crosslinking of proteins is of particular relevance to aquariums in this list.
You can find more information about this in the second part of the series: The story of liquid CO2 fertilisation – The Effect