The story of liquid CO2 fertilisation – The Reliability

In the fourth part of the series “ The story of liquid CO2 fertilisation ” we examine what we consider to be the most important aspect. The health of your animals but also of you, the aquarium owners is our number one priority. That’s why we would like to share some information about the active substance glutaraldehyde.

Is glutaraldehyde harmful and dangerous?

To what extent a product is classified as harmful or dangerous depends on the international directives about the classification of hazardous substances which are regulated in a legally binding form in the European Union in the “Regulation (EC) No. 1272/2008 of the European Parliament and of the Council of 16 December 2008 on the classification, labelling and packaging of substances and mixtures” as well as in the updates of the same regulation.

The effects of the substance depend on its concentration. The products on the market contain a solution with a 1 – 4 % share of glutaraldehyde. The following table shows the statutory declaration of glutaraldehyde in various concentrations as a hazardous substance.

According to the CLP Regulation glutaraldehyde is only removed from the classification as a hazardous substance when it is below a concentration of 0.5 percent. But even with lower concentrations the supplement “EUH208 Contains glutaral. May cause allergic reactions.” needs to be mentioned on the label.

100 % glutaraldehyde (pure substance)

Signal word: Danger Hazard statements: H301+H331 Toxic if swallowed or inhaled. H314 Causes severe skin burns and eye damage. H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled. H400 Very toxic to aquatic organisms.

Product containing 4 % glutaraldehyde

Signal word: Danger Hazardous component which must be listed on the label: glutural Hazard statements: H315 Causes skin irritation. H318 Causes serious eye damage. H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled. H317 May cause an allergic skin reaction. H335 May cause respiratory irritation.

Product containing 1 % glutaraldehyde

Signal word: Danger Hazardous component which must be listed on the label: glutural Hazard statements: H315 Causes skin irritation. H319 Causes serious eye irritation. H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled. H317 May cause an allergic skin reaction. H335 May cause respiratory irritation.

Product containing 0.5 % glutaraldehyde

Signal word: Attention Hazardous component which must be listed on the label: glutural Hazard statements: H315 Causes skin irritation. H319 Causes serious eye irritation. H317 May cause an allergic skin reaction. H335 May cause respiratory irritation.

Product containing 0.1 % glutaraldehyde

Signal word: omitted Hazardous component which must be listed on the label: omitted Hazard statements: omitted Additional indication: EUH208 Contains glutaral. May cause allergic reactions.

Summary: This product cannot be described as non-toxic or harmless and the providers of any products who do not label dangerous substances as such are deliberately violating applicable legislation and thus jeopardizing the health of the user.

From experience you need to set and to keep up a target value of at least 20mg/l CO2 to optimise plant growth with CO2. Instead of 1ml per 50L for a 50L aquarium the product needs to be dosed with 284.1 ml (with a 4% solution and realistic degradation) or 113.8 ml (with a 4% solution and complete degradation):

to achieve 20 mg/l CO2 in water, I need for a 50L aquarium (20 x 50) a CO2 amount in mg = 1000
in case a of complete degradation of glutaraldehyde you need for 20 mg/l CO2 the following product amount [ml] 11.38
in case of a realistic degradation of glutaraldehyde you need for 20 mg/l CO2 the following product amount [ml] 28.41

This results, whatever the degree of degradation, in the following amounts of glutaraldehyde in the water (in each case after the dosing):

results in a concentration of glutaral in the water toxic effect on fish toxic effect on aquatic invertebrates toxic effect on algae
in mg/l from from from
Dosage for a complete degradation to 20 mg/l CO2 9.1 11 mg/l 2.1 mg/l 0.9 mg/l
Dosage for a realistic degradation to 20 mg/l CO2 22.73 11 mg/l 2.1 mg/l 0.9 mg/l

This amount equates to the 10-fold amount to act as algicide, the 4-fold amount to become toxic for invertebrates and lies slightly under the amount to cause first toxic poisoning symptoms in fish (in each case with a 4% solution and an assumed complete degradation of the glutaraldehyde).

From the last column the biocidal effect of the products on algae is apparent, as mentioned by users. But: this substance has no approval as a biocidal substance.

If the user doses 1 ml/50L daily this leads to the following calculated CO2 production:

1 ml of a 4% glutaraldehyde containing product results in
mg CO2 (complete degradation) per 1 ml 87.91
mg CO2 (realistic degradation) per 1 ml 35.17
This corresponds to a bubble count CO2 of a compressed-gas system in case of complete degradation and 0.125 mg CO2 per bubble of 703.32
This corresponds to a bubble count CO2 of a compressed-gas system in case of realistic degradation and 0.125 mg CO2 per bubble of 281.33
Time available for the CO2 supply of 20 bubbles per minute [minutes] – in case of complete degradation 35.17
Time available for the CO2 supply of 20 bubbles per minute [minutes] – in case of realistic degradation 14.07
Number of possible CO2 bubbles per minute from glutaraldehyde containing product during a 12-hour CO2 supply (= 720 minutes) in case of complete degradation 0.98
Number of possible CO2 bubbles per minute from glutaraldehyde containing product during a 12-hour CO2 supply (= 720 minutes) in case of realistic degradation 0.39

In principle the users can supply their aquariums with carbon dioxide for 14 to 35 minutes per day (depending on whether complete or realistic degradation of the glutaraldehyde is a given) or, maintain an illumination time of 12 hours, with between 0.4 and 1 bubble CO2 per minute. It should become clear that this way of supplying plants with carbon dioxide results in rather homeopathic results and requires from the user a strong belief in the effect of the product.

The effect of glutaraldehyde as biocide, algacide or even as toxin is depending on its concentration and application.

Conclusion

“Liquid CO2”, based on glutaraldehyde, is a dangerous substance and is about 1.5 times more expensive than a conventional carbon dioxide compressed gas fertiliser system or about 15 times more expensive than the refill of a 500 g cylinder of carbon dioxide, if a concentration of 20mg/l CO2 is needed.

Is there a different method for the supply of carbon dioxide?

We have to mention here, that not all product suppliers, who advertise their products as liquid carbon fertilisers, are using the toxic substance glutaraldehyde in an aqueous solution.

At least one supplier has another approach, in that they integrate organic acids or sugar-like compounds in the formulation. This is not a bad idea, as carbon resources get consumed by bacteria, which use the carbon inside these compounds as an energy source (the same way as we use glucose as energy source) and release CO2 as an end product to the surroundings.

However we should not forget that for this bacterial carbon dioxide production the bacteria also consume oxygen. Furthermore you are “feeding” all the bacteria using organic substances as an energy source. These unfortunately also include species which also can trigger diseases in fish, when they are present in the water in higher density.

As yet there are no statistically significant results available for JBL to conduct a conclusive evaluation of the effectivity on plants of this kind of carbon supply.

Why doesn’t JBL produce a liquid plant fertiliser based on glutaraldehyde?

JBL rejects the production and distribution of glutaraldehyde containing substances for safety reasons and on ethical grounds. Please be aware that you are not doing your health any favours when using this kind of products. And keep the products away from children (safety note P102: Keep out of the reach of children.)

Conclusion: Carbon dioxide (CO2) is the most important plant nutrient ( Why is carbon dioxide (CO2) the most important plant nutrient in the aquarium? ) for water plants in our aquariums. But the significance of an additional dosing of CO2 is still being underestimated by aquarium owners. To eliminate the deficiency, carbon dioxide is required for the aquarium, and is added by means of pressurised gas cylinders or bio-CO2. Liquid CO2 is not available under normal conditions, as described in the introduction of this blog article, (temperature: 20 °C and atmospheric pressure: 1 bar or 1013 hPa).

© 06.07.2016
Matthias Wiesensee
Matthias Wiesensee
M.Sc. Wirtschaftsinformatik
JBL GmbH & Co. KG

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