The question: How does EI, or any other method where the aim is to keep all nutrients at levels that are not limiting, help control algae growth?
I have used such approaches with good results as have many others. I think most would agree that the basic principle is that all nutrients (including CO2) are provided at levels that are sufficiently high as not to limit growth. In such a situation light will become the limiting factor in terms of photosynthesis and plant growth. The result of such an environment is that plants grow quickly and are strong and healthy. It is generally accepted that where there is a sufficient quantity of plants that are healthy and are growing well then algae growth is limited. I have seen this as have many others. What I am interested in is why does this happen?
I've seen a number of mechanisms suggested over the years that i'll try and summarise here:
· The healthy plants outcompete the algae for nutrients. This is often suggested by people who I feel don't really get the whole principle behind EI (or similar methods) in that nutrients should be at levels that aren't limiting.
· Healthy plant growth controls levels of ammonia/ammonium in the water. I've seen two suggestions here; firstly direct competition i.e. the plants remove the NH4/NH3 that the algae need to grow. Alternatively the plants remove the NH4/NH3 thus creating stable conditions in relation to this nutrient with the result that algae are not encourage to enter reproductive phases as they might under less stable conditions.
· As above but not specifically in relation to NH4/NH3 i.e. generally stable conditions discouraging algae entering reproductive states.
· Plants produce substances that limit algae growth (allelopathy).
· Plants are growing fast and the process of pruning, replanting etc. takes place at a rate that is physically faster than that of algae growth.
I'd be really interested to hear peoples thoughts and knowledge of any evidence (including from outside of the aquarium hobby) that points to any particular mechanisms that may be responsible.
Thanks
Neil
I have used such approaches with good results as have many others. I think most would agree that the basic principle is that all nutrients (including CO2) are provided at levels that are sufficiently high as not to limit growth. In such a situation light will become the limiting factor in terms of photosynthesis and plant growth. The result of such an environment is that plants grow quickly and are strong and healthy. It is generally accepted that where there is a sufficient quantity of plants that are healthy and are growing well then algae growth is limited. I have seen this as have many others. What I am interested in is why does this happen?
I've seen a number of mechanisms suggested over the years that i'll try and summarise here:
· The healthy plants outcompete the algae for nutrients. This is often suggested by people who I feel don't really get the whole principle behind EI (or similar methods) in that nutrients should be at levels that aren't limiting.
· Healthy plant growth controls levels of ammonia/ammonium in the water. I've seen two suggestions here; firstly direct competition i.e. the plants remove the NH4/NH3 that the algae need to grow. Alternatively the plants remove the NH4/NH3 thus creating stable conditions in relation to this nutrient with the result that algae are not encourage to enter reproductive phases as they might under less stable conditions.
· As above but not specifically in relation to NH4/NH3 i.e. generally stable conditions discouraging algae entering reproductive states.
· Plants produce substances that limit algae growth (allelopathy).
· Plants are growing fast and the process of pruning, replanting etc. takes place at a rate that is physically faster than that of algae growth.
I'd be really interested to hear peoples thoughts and knowledge of any evidence (including from outside of the aquarium hobby) that points to any particular mechanisms that may be responsible.
Thanks
Neil