Phenols, how dangerous they are for a seawater aquarium ?

[Frankie]

After reading hma's wonderful write up in his thread I thought I would get it out on the front page for all to read

In the sea water aquarium, apart from the inorganic eliminations of the fish and lower animals (e.g. ammonium, phosphate), also organic waste is produced. The firm components (excrement, alga remainders, food) are held back in mechanical filter. However, they are also converted by bacteria. Compounds arise, which ones can biologically be decomposed not or only very slowly and difficultly. These substances are coloured partly yellowish.
The so-called yellow-substances in the seawater aquarium consist of phenols, phenolic compounds, excrement-coloring, Alga pigment, Carbohydrates from secretions of algae as well as animal faeces containing nitrogen. The yellowish colouring of the water gives the aquarium an unnatural appearance.
While the substances eliminated by animals and algae can be poisonous (ammonium, nitrate), the yellow substances are, if they are present in small quantities, alone not so very dangerous. The phenols and phenolic derivates (organic compounds) are neurotoxins. They damage the epitheliums of gills, intestines and skin of the fish, though. About the blood circulation liver, musculature and ovaries are also attacked.
Since the phenol concentration often is not provable in the seawater, these compounds often are of subordinate importance for the reefer. With too high quantities, however, it comes to poisonings which are usually incurable. The excretions of the fish (urine, excrement) charge the water of the aquarium in the long run.
Sufficient attention is not generally given to this fact, simple therefore, because nothing visible happens. The poisonous nitrogen compounds must be brought out from the aquarium by water changes or dismantled by means of suitable filters and filtering materials. This reduction is carried out by bacteria: Nitrosomas convert ammonia into nitrite Nitrobacter into nitrate. The yellow substances can easily be removed by ozone, skimmers and activated carbon out of the water.
Phenols are chemically seen hydroxybenzoic. These contain one or several OH-groups directly at the benzene ring boundly. Phenol (C6H5OH) is a colourless compound from the aromatic row. They are white in purely crystalline form. Phenol has both the quality of weak acids and these of alcohol. The OH-group makes it possible easily to react and to come in connections with many substances of the surroundings. Particularly many reaction partners are in the seawater at the disposal.

Phenols are not available in the sea in uncombined form. The cyclical amino acids (degradation products of proteins) are easily oxidized by bacteria in the aquarium. Among other things phenols also arise at these oxidations as temporary intermediate products. The only short existence of phenols is awkward there can exist a toxic effect on our animals.
At existence of sufficient oxygen phenol, however, is oxidized to pigments (yellow sting!). These pigments are not dismantled any more and collect in the water. These yellow substances can be reduced again to phenols at too little oxygen in the seawater. A good skimmer guarantees a sufficiently high oxygen exchange in the water. The yellow substances and other not coloured organic compounds from the secretions of the fish, invertebrates, corals and algae seem partly impeding to the low growth of algae and animals. We measure the pigments with the help of a white plate which is partly dipped into the aquarium. The dipped plate part should be as white as the outstanding one. This is the simplest opportunity to prove phenols in the seawater aquarium, I have already mentioned this procedure way in other articles, too. There is the possibility in the meantime of proving phenols with a droplet test too, developed by the company Merck chemicals.
Phenol or phenolic compounds are highly-poisonous. There are the possible reactions with chemical substances in addition, which ones are possible in any seawater aquarium. Phenols are so-called cytotoxins, which attacking the DNA of the nucleus of a cell and leading to changes there. Endogenous proteins can be damaged too and in addition, the normal function of the enzymes can be changed, what in the organ system leads to being missing controls. It was noticed with coral fish that these already at 0.15 mg of phenol per litre aquarium water got eating bored and died without broader outer symptoms short time later. Phenols are very likely the most frequent reason for an inexplicable death of fish in the aquarium. By the use of ozone, activated carbon as well as strong skimmer phenolic compounds can be removed in a simple way.
With a small set of of phenol and his derivatives they are included and removed without problems of protein skimmers. There are, however, phenolic compounds (primarily in larger quantities), so the normal foam caves in. Through this the nitrogen values (nitrite) rise and furthermore it can lead to so-called toxic peek. Only if the skimmer forms a normal water air mixture again, a scum effect stands up for proteins again and the nitrite values will drop slowly again. The external appearance and the behaviour of the foam make sure conclusions possible on a pollution of the water. One can carry out a fast sample by filling a bottle with aquarium water half-filledly and shaking these strongly (shaking test). Then one watches the behaviour of the foam. With unloaded water the foam disintegrates fast while with loaded water the foam stops.
The phenolic compounds also damage the bacteria cultures in the aquarium. Both the nitrification bacteria as well as the denitrification bacteria are affected. Since the yellow development of the water has to be watched however also in very well neat seawater aquaria (Phenol test was negative.), such other factors must be causal for the colour fault. The excrement pigment (bilirubin) is one of the possible further reasons for it. The red blood corpuscles die after a certain time and are replaced by new formed, this happens constantly. The numb red blood corpuscles are dismantled by the liver and eliminated over the gall and the intestines of our fish. They form the so-called excrement pigments, like bilirubin and biliverdine, which one also responsible for the yellow colouring of the water to a good part. This process is mainly to watch in pure fish aquaria, so-called FO (Fish only). Another reason for the yellowish discoloration is the reduction of algae pigment. Should get the water yellowish in a well neat reef aquarium with a good skimmer, so the reason for it is not always the being of phenols but often either one of the other factors mentioned before.
I hope this short article helps to know what actually are phenols and a little better to understand what they can cause but also what, on the other hand, you can do against it.

Heinz Mahler, Nov. 2008

For the complete article please follow this link:
Phenols, how dangerous they are for a seawater aquarium
Thank you Heinz for all your hard work and contributions to this wondrous hobby. You are a unique member to our forum!

[sambrinar]

Thanks Frankie, this is very interesting, we use Phenol in my office to kill the nailbed of a toe after the nail is removed (b/c of ingrown) to prevent the toenail from growing back. this stuff smells like fermaldahyde (sp). If that tells you how potent it is in pure form

I had to make sure it was the same thing, yep. Very interesting reading, I will have to be sure to thoroughly wash my hands after using this.