algae+co2=?

[krap101]

in school im learning about like.. ecosystems. too much of a limiting nutrient=algae bloom. etc etc. does co2 help or kill algae?

 

[QuantumCranker]

It doesn't do either really. What it does is optimize the plants ability to take in nutrients and thus speeds up their uptake so that the algae, being much more primitive is robbed of or never gets a chance at the nutrients. When there is a nutrient imbalance, the plants slow down, and the algae will triumph because it doesn't need as complicated a list of things to survive. This is why you often see the advice to pack a new tank with fast growing stem plants first when high light is used. The CO2 "drives" the plants harder. Algae usually never has a fighting chance.

 

[AlexPerez]

so that the algae, being much more primitive is robbed of or never gets a chance at the nutrients

Nutrient Limiting the Algae just doesn't make sense. There is always more than enough nutrients in a fertilized planted tank for the algae. If the Plant have enough then so do the algae. Nutrient limiting for algae can't be right. There has to be more to it than that.

 

[malkore]

One thing that's theorized is that when plants are growing healthily, they produce a lot of allelochemicals...these act as inhibitors for algae growth, and in some cases inhibit other plants growths. Not a lot of research has been done on these chemicals yet, or to see if plants have their own unique version. I do know that anachris produces quite a bit of allelochemical.

This theory certainly seems supported by what we observe in our tanks: when nutrients are balanced, algae seems to disappear. Algae doesn't seem to like CO2 very much. I think its too simple an organism to be able to use the extra CO2...really algae just wants to colonize...it's purpose isn't to photosynthesize like crazy.

Now, if you really wanna shake things up: Seachem Excel, while not marketed as an algicide, is VERY effective at blocking algae growth. YOu can take it step further by using Gluteraldehyde...the pre-cursor chemical that Excel is based on...and algae really cannot tolerate this stuff. Its supposed to be a simple carbon supplement in place of CO2, but man it does wonders to ruin algae growth!

 

[QuantumCranker]

Nutrient Limiting the Algae just doesn't make sense. There is always more than enough nutrients in a fertilized planted tank for the algae. If the Plant have enough then so do the algae. Nutrient limiting for algae can't be right. There has to be more to it than that.

What I meant was that plants are draining nutrients out of the water column so fast when they are at their best, that algae, which is usually caused by excess of one and lack of another, has no excess nutrients to go on. Obviously, this works better BEFORE the algae gets started than once there is already a large amount of it. In a nutshell, if you feed the plants with algae present, you are feeding both plants and algae, if you feed the plants RIGHT with no algae present, there is not enough excess nutrients to support a large amount of algae.