Underlying theory of algae control ?

[gpontis]

I have been reading these forum articles on algae with some interest. I can't figure out the root cause for algae growth or the reason for why it is controlled when following the general recommendations here. Here are the points that I am seeing. Some help please with pulling the ideas together ?

First, most of what I am reading is focused on optimizing plant growth conditions. For example, that would include EI, N/P ratio, and high CO2. I have not seen Tom say that any one of these, such as the N/P ratio, has a magic effect on reducing algae growth.

Second, the design of EI (as I understand it) ensures that plenty of nutrients are always available. Thus, algae control cannot depend on the plants doing so well that they out-compete the algae for nutrients since we are ensuring that it will not happen.

So at this point I gather that we have created an environment that is great for growing plants and equally good for growing algae. I am not seeing a relationship between growing plants and growing or not growing algae. In other words, it looks to me that one could remove all the plants and the growth or lack of algae growth should not change. Is there something about high CO2, for example, that reduces the rate of algae growth ?

NH3/NH4+ is shown to be a strong promoter. If that is the primary causative for unwanted algae growth, is it possible that a well planted aquarium is controlling algae by sucking the NH3/NH4+ out of solution very quickly ? If this is so, then we should also be paying attention to sources of NH3/NH4+ and our non-plant biological filters. Maybe minimizing the sources of NH3/NH4+ would be the most important and primary factor to get under control if it is not already in control ?

 

[Tom Barr]

Re: Underlying theory of algae control ?

First, most of what I am reading is focused on optimizing plant growth conditions. For example, that would include EI, N/P ratio, and high CO2. I have not seen Tom say that any one of these, such as the N/P ratio, has a magic effect on reducing algae growth.

And you won't
CO2 might be the closest thing, since algae are virtually never carbon limited, while plants mostly are.

Second, the design of EI (as I understand it) ensures that plenty of nutrients are always available. Thus, algae control cannot depend on the plants doing so well that they out-compete the algae for nutrients since we are ensuring that it will not happen.

Yes, this bugs folks a lot.
But when you compare apples to oranges, well, that's a very big assumption too many still make today even.

It's like saying a mouse(algae) and an elephant(plant) are on equal competitive and reproductive terms. Both are herbivores.

The difference is even larger with plants/algae.

In other words, it looks to me that one could remove all the plants and the growth or lack of algae growth should not change. Is there something about high CO2, for example, that reduces the rate of algae growth ?

No, something will grow there. I tried a number of gas levels both CO2 and O2 and measured surface area of algae colonization. Every comination(6) without plants had the same algae biomass.

NH3/NH4+ is shown to be a strong promoter. If that is the primary causative for unwanted algae growth, is it possible that a well planted aquarium is controlling algae by sucking the NH3/NH4+ out of solution very quickly ?

Yes.

If this is so, then we should also be paying attention to sources of NH3/NH4+ and our non-plant biological filters. Maybe minimizing the sources of NH3/NH4+ would be the most important and primary factor to get under control if it is not already in control ?

Yes.

But variations in the plant health due to other things besides NH4, causes slow downs, once your tank gets going and has no limitations for the plants, then the algae subsides. Generally takes a couple of weeks of patience.

Regards,
Tom Barr

 

[Denis Onii]

What I would like to find out, is how much algae is due to changing conditions. Everyone talks about ratios and concentrations but it seems to me, with a limited understanding of plants, that the best way to reduce, even stop algae is by interrupting it's life cycle and stopping meiosis.

Problem is there are many variations in the life cycles of algae and I wouldn't know which one applies to what but in terms of algae that produce dormant spores, in seems common sense that spores are produced/released in response to deteriorating conditions in the environment, it wants to survive for a period of time, say the winter so it is watching for a change in something, could be temperature, salinity, N, P, Si, light or a combination of these. Once this "trigger" occurs, it releases spores that then sit around waiting for favourable conditions before germinating. Problem is that in a tank, the condition that caused spore release is then quickly fixed by the owner and this immediately causes the spores to germinate.

In this way, an algae bloom is caused by two triggers, the depletion of something followed by it's fix. I wouldn't know how or if this would apply to zoospores.

If this is true, then in theory, a tank that could maintain fixed levels of potential trigger variables (temp, N, Si etc) would not get any algae at all (as long as those levels are already outside any trigger value)