Fighting algae with plants

Algae are a natural phenomenon. They are normally present in all aquatic ecosystems.

Algae, hated in aquariums and ponds!

We do not like them in our aquariums for aesthetic reasons, but that is the only real problem they cause. Of course, in the subtle competition between plants and algae, we do not like algae to win, becoming so dominant that they end up smothering our plants.

 

Algae are everywhere in a newly set-up aquarium.

 

Again, this is a natural, temporary, and unavoidable phenomenon.

It is actually the main business of sellers of magical bottles that usually have no effect. If your algae disappear by coincidence at the same time, they will say it is thanks to the product. And if they persist, it will be because you did not follow certain rules!

 

Personally, I have never been very convinced by the reflex that consists, when faced with a "problem" (algae, scary critters, snails…), in killing the problem, forgetting that it is part of a complex system that brought it there, fed it, and favored it.

Especially since there is no active product (biocide) that does not have side effects on other species, at least microbial ones.

And then, you go back to the seller to buy the next bottle, supposed to solve the next problem, actually caused by the first one!

 

As for me, I do not always fight against algae.

In my most natural aquariums, I let them come and go on their own. Then the aquarium ages and only a few discreet Cladophoras remain, which do no harm to anyone!

When I start an aquarium, knowing that the first year will inevitably be eventful (balance is not decreed, it is sought and found on its own), I use a natural weapon to temper excesses.

Clearly anti-algae plants

Since my youth, I have noticed that elodea and Egeria najas, which are close relatives, are almost always free of algae.

It was recently discovered that these plants secrete a molecule very close to antibiotics, thus having an effect against cyanobacteria. Since cyanobacteria are classically the forerunners of algae in a young aquarium, the presence of these plants seems to greatly hinder the establishment of algae.

 

So I always place stems of these two plants (because they probably have slightly different actions) in aquariums where I want to limit or even prevent algae.

 

In recent years, I have tested their action (Egeria najas and elodea) in tanks being overrun, where cyanobacteria are already giving way to the first true algae.

The result seems quite convincing. It takes a little time but, after several weeks, you begin to see a decline in algae.

My few aquariums fully packed with elodea or Egeria najas are completely free of algae.

 

I think it is not just the effect of the secreted molecules, but that algae already in poor condition are then fatally outcompeted by these exuberantly growing plants whose needs are probably very close.

 

When algae have nothing to eat and plants send them clouds of natural but toxic molecules, they insist less already!

 

 

Playing competition against algae

Because it is also true that competition for resources is fierce between plants and algae.

Algae are themselves plants, and they have quite similar needs: nitrogen, phosphorus, potassium, light... The more your plants consume these resources, the less they leave for algae.
This angle of natural anti-algae struggle can be enough to keep algae in check in low-tech aquariums or natural ponds

In this case, why not think, besides elodea and Egeria najas, of the famous Hornwort, champion of growth and thus of competition? Pretty, frost-resistant in ponds, exuberant while letting light through, the famous Hornwort is an excellent candidate for the trophy of anti-algae plants!

The same strategy can lead you to Limnophila, which grows wildly in summer and effectively cuts the ground from under algae. But Limnophila fears the cold and, unlike the previous ones, will only work in summer, where it often outperforms them.

Another path: the phosphorus war with Azolla.

Algae are favored by high phosphate levels.
And few plants manage to correct this, since they consume less than algae.
Hence the interest of Azolla, a floating pond or aquarium plant, which devours phosphates. Azolla filliculoides is an outstanding purifier, even used at the outlet of some mining facilities to clean waste waters!
It is therefore impossible, especially in ponds, to do without this unique plant, which often withstands all seasons, even if it grows faster in summer.

 

Plants are therefore a true Swiss army knife, each fulfilling a role against algae in aquariums and ponds, all complementing each other for maximum effectiveness.
And all this without harming the subtle and fragile ecosystem of your aquarium.

 

To learn more about the origin of algae in aquariums, a must-read article: Where do algae in aquariums come from?

And if Azolla intrigues you: Azolla, nature’s Swiss army knife