There is quite a bit of debate regarding aquarium plants and allelopathy. Do live aquarium plants emit chemicals into the water to combat algae? Tests in controlled environments are inconclusive at best. While it is true that having live aquarium plants reduces algae growth, there are a number of factors that must be considered.

Aquatic plants are only one part of a thriving ecosystem which consists primarily of live aquarium plants, light, and fish. After reading my verified opinion, you’ll understand the importance of having aquarium plants in your tank.

Live aquarium plants and algae have similar needs. A healthy tank, with a variety of aquatic plants and fish, does not encourage algae growth. For this reason, allelopathy seems to be having an affect.

It is easy to see how one could conclude that these aquatic plants are releasing anti-algae chemicals into the water. Without enough live aquarium plants, algae fills the role of absorbing carbon compounds, and as algae grows, the flora becomes further weakened. Sufficient live aquarium plants kill algae by competing more efficiently for the chemicals and nutrients available via fish waste or dissolved fish food. Rather than emitting chemical agents, aquatic plants are better able to take away the chemicals which are already there.

And here we see the role of fish in maintaining the health of aquarium plants. Not only do live aquarium plants provide shelter for fish and add decoration, aquatic plants also provide a natural cleaning system, recycling carbon dioxide into oxygen, converting fish waste into fertilizer for aquatic plant growth. Once a healthy amount of lighting is provided for live aquarium plants and fish both, you’ll see how aquatic plants play such a vital role in the tank.

In a very real sense, allelopathy is going on, perhaps not in a way that is poisonous to algae, but in a competitive fashion. Algae growth is a sign of the tank being out of balance, possibly because there aren’t enough aquatic plants. Adding more live aquarium plants, and making sure that the aquatic plants are getting eight to 10 hours of light per day should help. A weekly check of pH (using pH tester) and gH balances should be sufficient when there is a healthy balance of fish and aquarium plants. Allelopathic symptoms occur as healthy aquatic plants push out algae growth.

Using aquatic plants is a natural, beautifying method of controlling algae growth, beyond a doubt. Live aquarium plants provide a necessary link in a tank’s ecosystem.

David