Fighting the algae with Hydrogen Peroxide - Ι
by George J. Reclos
Algae is a very common problem in almost every tank - especially planted ones. Indeed, aquatic gardeners go to extremes to make sure that the conditions of their tank favor the growth of normal plants instead of algae. They "play" with the concentrations of the nutrients (even the micronutrients), the lighting period, the quality of light (intensity and spectrum) and have long lists of "do's" and "dont's". Of course, they don't get rid of the algae. What they do is to keep it under minimal growth conditions, a lurking enemy which will wait till something goes wrong to take over the tank. I like plants a lot, especially in my tanks. However, I am not willing to go to the extremes I read in order to have the perfect planted tank. I leave this task to others. I admire the tanks of Takashi Amano and many others (like Tolis Ketselidis and Pavlos Aslanis ( http://www.bellybean.com/~pave/aquaria/ ) tanks - to name two Greek hobbyists) but I never "felt" the urge to create something similar. To me, aquarium means aquatic life but mostly fishes. I like the movement, the personality, the behavior of those creatures and this is why I am focused on cichlids and Mediterranean marine fish. I have quite a few tanks with plants one of which (the discus tank) is heavily planted. I really don't mind having some green algae in there - in fact I like it. After all, algae will consume ammonia and nitrates thus giving my fish a healthier environment. However, when I saw an ugly black algae invading my tank everything changed. No, I didn't like it at all, it was one of the ugliest things I have seen growing in any of my tanks. A friend had donated me some plants and it seems that the conditions of my tank favored this particular algae more than my plants. Soon, the algae was everywhere, black / gray, ugly, long, blocking the light and suffocating my plants. Removing it by hand was impossible - I would tear the leaf apart - even uproot the plant while dragging the algae - but in the end the algae was still there. Thanks to Pavlos, I found a board and read some tons of messages concerning this kind of algae which was nicknamed "devil's algae" since it seemed that all commercial algicidal products in the market were unable to stop it. In fact, after running a test in a small tank, it seemed that they promoted the growth of black algae - perhaps by eliminating all or some of the competing algae types.
After reading more, I found out that you may not be able to avoid the presence of algae in your tank but you may modify the conditions to favor one kind of algae over another. And once the "wanted" kind of algae comes in your tank, the unwanted one finds it far more difficult to survive. A key factor mentioned quite a few times in those messages as well as a couple of article I read was the "redox potential" of the water. It seemed that the dreaded black algae which I had in my tank didn't like oxidizing agents. In contrast, green algae seems to do far better in such an environment, in fact it may even thrive. I made some research confirmed that my fish wouldn't have any problem if the redox potential was raised within some limits.
The black algae has covered every inch of my beautiful Microsorium pteropus
This leave is barely seen under the thick coat of algae. The algae completely covered all leaves within one week.
This is how the outlet of the internal filter looks like. When I tell you this algae was everywhere I mean it.
Increasing the redox potential of the water is a risky issue. Fortunately, there is a chemical which will do exactly that, is cheap, available everywhere and - the most important thing - its only metabolite is water and oxygen. Ladies and gentlemen welcome hydrogen peroxide. The concentration most usually found in the pharmacies is a 3% solution which is exactly the concentration I would need according to the information I had collected. I had two options: adding it slowly in the water column and adding it directly on the black algae. For those who know me, it is obvious that the most radical option would be the one I would choose.
Sixty ml of a 3% hydrogen peroxide solution are slowly released over the affected area with a syringe (needle detached of course). Three such injections were made in the tank, one of them used exclusively for the heavily covered M.pteropus.
Within seconds, bubbles of nascent oxygen are visible on the algae. Well, now this is something working - at last. After a few minutes, the whole tank was full of oxygen bubbles and the fish really enjoyed it.
Another photo showing the oxygen bubbles formed on the black algae. When I saw that I was already worried about the fate of the plants but there was no other way. With this kind of algae, you can't leave any plant in the tank. You have to remove everything, cut almost all leaves and then start from a scratch. Therefore, even if only part of the plants I had survived it would still be a success.
Continued in next page