Why Does The Estimative Index Reduce And Prevent Algae?

[nry]

Okie dokie - I get the drift about adding enough fertiliser (inc. CO2) and light for plants to grow well, but we still end up with excess values of everything we add. Why does algae not simply use this excess?

 

[Underwurlde]

Because plants produce a chemical inhibitor (chemical warfare) on algae and indeed on each other and even on the bacteria gobbling up all the oxygen in the filters. Allelochemicals I think they're called. I still can't say that stupid word.

Andy

 

[kris Dearman]

hey it will take time for the alga to grow its a slow growing organism it will however take over if your not carful just wait and see it will use it as a food source good luck

 

[Underwurlde]

...Infact algae do the same. They produce their own allelochemicals that inhibit plants. Some kinds of allelochemicals produced by algae are also very toxic to certain species of fish!

Andy

 

[Dave Spencer]

hey it will take time for the alga to grow its a slow growing organism it will however take over if your not carful just wait and see it will use it as a food source good luck

Algae is far more adaptable than aquatic plants and will respond to any changes far quicker. It certainly isn`t slow growing.

The Estimative Index ethos is to overdose the water column with nutrients so that the plants can become lazy and grow rapidly without having to move nutrients around or waste energy to produce rubisco. It is this scenario that algae hates and will keep it at bay.

George sent me an article on allelopathy a while back, but for me, the jury is out on that one. Why would plants inhibit growth, but not other species of plants? Rotala and Hygrophila growing side by side would be in competition surely, and try to inhibit eachother`s growth. Plus, how does allelopathy work in a fast flowing stream where all the chemicals are washed away? It`s an interesting subject, but I am yet to be convinced.

Dave.

EDIT: further to your question NRY, algae needs a germination trigger, in the form of light, NH4 or unstable CO2. Running the fertilisers we dose to excess will feed algae, but they do not trigger it. So, provided you are doing everything right, algae will not be triggered by excessive dosing.

 

[Underwurlde]

Why would plants inhibit growth, but not other species of plants?

They do. Well, some species wil effect certain others, etc.

Plus, how does allelopathy work in a fast flowing stream where all the chemicals are washed away?

But so will the algae?....

 

[Themuleous]

I think Tom Barr ruled out allelopathy using activated carbon in a filter, which would quickly remove any such chemicals.

For me EI is quite simple. It creates a very stable environment in the tank very quickly (thought both keeping the fert levels the same and having lots of plant growth). Algae are your classic opportunistic plants, that will take advantage of situations when other plants will be struggling. Sudden changes in an aquatic environment require higher plants to acclimatise themselves, this 'lag' period is the algae's opportunity to thrive relatively unhindered. So they algae germinate and grow, often taking over that environment and stopping the plants from ever re-sabilizing it.

A phase Tom once said I will never forget.

'Its not that algae cant grow, its that they aren't given the cues to germinate'

Sam

 

[nry]

I'm also not sure on the alleopathy thing (but I haven't read anything about it so I don't know either way), EI has certainly worked for me (though I have some persistent thread algae on my glosso) and I do not doubt it works - in short it purely comes down to stability of the water column from what people are saying.

Such stability is, I am guessing, hard to maintain el-natural (or will if nothing else take much much longer to attain) which is why EI works?

 

[JamesC]

There is a great article on Allelopathy on Tropica's website - http/www.tropica.dk/article.asp?type=aquaristic&id=531. You can draw your own conclusions from this article but the one thing that is said is that you will not be able to control algae in an aquarium using allelopathy.

The two things that I believe control algae and what I strive to maintain are lots of 'happy' plants and stability. By happy I mean plants are given everything they require to grow. Too many people want instant results and keep fiddling with everything and then wonder why they keep getting algae. What start's algae growing? IME ammonia from either a poorly maintained tank, substrate disturbance or 'unhappy' plants leeching ammonia back into the water column. Possibly the reason why algae grows on leaves of plants that are suffering and not on healthy plant leaves.

James

 

[Themuleous]

Possibly the reason why algae grows on leaves of plants that are suffering and not on healthy plant leaves.

Interesting idea that James, would certainly make sense. The NH3 thing is also a good point. I guess this is why people tend to under stock, to reduce the risk of the fish waste NH3 being a problem.

Sam

 

[Underwurlde]

Great stuff!

Fundamental question still remains though: Regardless of stability etc. in an EI tank there is bags of everything a plant-like organisim needs to grow. So, why not the algae! WHY would stability impair the growth of algae?

Does carbon remove allelochemicals? If it does, it would only do so for a day or so before it became loaded....

Anyway, I have not made my own tests / research. I only stand on the shoulder of giants and try to skim the creame of their understanding & make (some) sense of it all.

Andy

 

[Themuleous]

Stability does impair growth, it stops the algae from starting to grow in the first place, by not given them the cues to germinate

To be honest, if Tom says he's used carbon to remove the allelochemicals (if indeed they are even present) and he found no difference, then thats good enough for me!

Sam

 

[JamesC]

Forget about allelopathy in a planted tank. Even if it exists in aquatic plants and algae there is no evidence that is has any effect in our tanks. If it did it would have been used as a wonder cure long ago I'm sure. Would make life far too easy if you could grow a certain plant that would kill all your algae.

Plants need nutrients and so do algae. Algae can live on a lot less than what plants can so trying to remove nutrients is going to prove futile as plants will suffer before algae do. Try leaving a jar of RO water on your windowsill and see if algae grows - it does for me anyway. Now try and grow plants in it??? What I trying to say is that what ever way you keep your tank there is always going to be enough nutrients for algae to survive, be it by adding loads of nutrients or trying to strip them out using chemical media. This old idea that plants remove nutrients before algae can get to them is just nonsense to me. I'm a firm believer in ammonia being the main cause of algae. This is the trigger for algae to start growing. Prevent ammonia by keeping a maintained tank and healthy plants and you should'nt have algae problems. Easier said than done though. I currently have a small amount of Green Spot Algae on my old Anubias leaves which isn't a problem, only just a little bit unsightly. Otherwise even under carefull scrutiny I cannot see any trace of any other algae. I sometimes do have a problem and it can always be traced back to either an ammonia spike or a nutrient problem causing an unhappy plant.

These are just my views and observations and what I believe in so may be incorrect, but they work for me.

James

 

[Underwurlde]

This old idea that plants remove nutrients before algae can get to them is just nonsense to me.

I agree.

Try leaving a jar of RO water on your windowsill and see if algae grows - it does for me anyway.

Andy for me. But then you say:

I'm a firm believer in ammonia being the main cause of algae.

There will be no ammonia in a jar of RO water, so clearly not the 'cause' perhaps?

Forget about allelopathy in a planted tank. Even if it exists in aquatic plants and algae there is no evidence that is has any effect in our tanks. If it did it would have been used as a wonder cure long ago I'm sure.

But isn't this exactly what we're saying perhaps? That the presence of growing plants in some manner inhibits algal growth, in other words techniques that allow plants to grow well such as EI and 'El natural', because they do this are the 'wonder cure' to algae. IF done properly, there is no / very little presence of algae in these tanks, Again why is this?

Still in my tiny brain there is clearly 'something going on' - the presence of healthy growing plants must in some way be inhibiting the algae. I stand by the allelophathy theory as nothing else seems to make sense.

Andy

 

[JamesC]

I understand what you are saying and to be honest I don't know the answer. I said that ammonia was the main cause and so therefore there are other causes as well, including whats in the jar of RO water. Fill a tank with fresh water and lots of light and you end up with algae. Do the same and add loads of fast growing plants and get no algae. Allelopathy would seem like the obvious answer but I'm not so convinced. Why? Because setup the same tank with the plants but rather than have an enclosed system, you have a continual change of water. What happens? - No algae. If there were allelochemicals then they would have been flushed away.

James