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We were lucky to get plant phys at all. I'm going to have to wait for PhD stuff to get the more advanced plant sciences. :( But anyway, back to algae and "new school".
 

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plantbrain said:
...

Regarding mulm and DOM build up.

I'm not sure it's the presence of these, but rather the loading rate.
If the loading raste exceeds the bacteria break down of these, then you'll get BGA or BBA I think also.
So does this therefore mean that you avoid the whole problem by not having any (at least visible) mulm and DOM? And clean your cannister filter at least once a month to get any organics out of there too?

Then you don't need to worry about loading rates...

Or is this too simple? :)
 

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That's how I took it to mean. I have a substrate loaded with organics (florbase) and haven't cleaned my filter in months and I've got BGA up the wazoo. I'm going to clean the filter today and see what comes out.
 

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In answer to the original question:

I know that the most widely accepted answer isn't always the correct answer, but I think in this case that it is. Aquariums generally tend to have a much higher fish to gallon ratio than most natural water systems, which leads to having high amounts of organics and nutrients, which has been discussed alread at length. The reason that new school aquariums have less or no algae is because of the high light and CO2 which allows plants to grow fast enough to use up at least some of the nutrients. The plants don't have to use up all the nutrients, just one or two essential ones that algae needs. This could be phosphorous, in the form of phosphates, it doesn't matter. But why can the plants outcompete algae? Higher forms of life are better adapted to survival in their environment; Humans use their brains to survive, carnivors their strength, plants...their ability to take up nutrients even in trace amounts very quickly, begin photosynthesis faster when the lights come on, etc. This only works, however, when there is not a surplus of nutrients, when there is not enough to go around. In an environment where there is plenty to go around the weakest still get their fill even if they have to wait until after the stronger organisms have taken what they want. In the case of the planted aquarium, the plants are the higher life forms and as such get first go at the available nutrients while the algae uses up the remnants. If there is enough light and co2 for the plants to grow quickly enough to use up all of one or more nutrient, then the growth of the algae will be retarded or stopped. In my personal aquarium I have too many large clown loaches for the gallonage of my aquarium and thus too much nutrients for the plants to use up. The result is that I have algae. When my loaches were small and i fed them much less I had near zero algae, but now they are large and I have to feed them more to keep them healthy so my plants, no matter how quickly they grow are unable to use up the nutrients so that the algae growth is resticted.
 

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Kay, well you kinda tore apart every little piece of my post, but you still never really answered the question at hand. You've given a lot of reasons why my idea isn't correct, but still haven't answered the original question with any sort of clarity. I was just making observations from my experience, I'm not the expert here, so you don't need to be malicious. But please, offer your theory then. The last part of your post came closest to finally offering some insight into why algae stops growing. If you do know why, I'd love to hear, please try not to be so cryptic.
 

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Hi,

I think I have to have a check up for my eyes, because I haven't noticed such a useful thread like this until today. So my opinions regarding to this matter will be as follows.

IMO, I have always believed that plant growth and health is the key element for algal growth. As long as you had nicely growing plants algea will never get hold on them and you will always keep algal growth at bay. Everything we do for preventing algea (except bleech, H2O2, some chemicals, etc… which I never use) IMO is in fact for promoting plant growth and not for causing alg to suffer nutrient defficiencies as alg have the ability to utilize minimum quantities of nutrients, lights, etc. regarding to the plants. So having good growth and sufficient amount of plant were the only options here.

But after I have read this thread, I started to wonder the reason why and how good growth may effect the algal growth even tough algea will never have a problem for nutrients and light at our tanks. And I believe that this is the main concern for this thread. Wright? So I made a cross check for algal growth and plant growth and added some of my experiences to reach a conclusion.

IMO there is only two types of algea regardles of color, size, shape, etc. and these are due to their positions, mobile and immobile algea. Mobile ones are the ones propelled by their flagella can move in the water, and some have specialized cells called holdfast to get a grip on things, hence immobile. To maintain their position, most algae use specialized cells called holdfast cells. These cells do not partake in reproduction or photosynthesis processes, they simply grab hold of ground or a rock and they hold the rest of the plant there. This anchoring system, does not take in nutrients like plant roots do.

For mobile alg besides the good plant growth at our tanks there are also some other factors that helps us in our tanks to battle them. They are softer and this greatly helps for some critters to consume them easily (like the green water). If there is a sufficient amount of current in the water, photosynthisizing is a bit harder for them and this will prevent the growth for them. That's why still water has a disadvantege for being overrun by algea.

For immobile algea the favors are a bit against us and this type is also our main trouble at our tanks. By means of their holdfast cells they can attach to any place for best use of light and nutrients and their first choice is always organic places likes the leaves of our plants. After then they may attach to rocks, gravel, plastic, glass but this time holding will not be that strong and nutrient and light will be harder to reach. So here, our main concern is to prevent them attaching at our plants. Water current at our tanks will never be sufficient to deattach the holdfast cells. But for these cells to attach properly, they need the surface to be smooth and motionless. So enhancing the plant growth simply makes the surface of the leaves change continuously and for algea imposible to attach these leaves. Thats why we usualy see algea only at dying or completely stunted leaves, or glasses at our well maintained, algea free tanks.

Lakes were also mentioned at some posts here. But the situation with the lakes are a bit different than our tanks. Water change is continuous, nutrients are abundant, alg eating creatures are abundant, water movement continuous, lighting is much much better, plant growth and qauntity is more than sufficient. So algea infestation is not possible except some placid lakes. Besides O2 quantity is not that much of an importance for me. If it had been, H2O2 would make more than wonders for all algal problems.

So as a conclusin for this awfuly long post, I would say that what fertilizer dosing style and quantities and ingredients, lighting you choose, they are not the main issue here, maintaining adequate quantities of good plant growth with continuous leaf surface change and having some current in the tank are.
 

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Tom (and anyone else who'd like to chime in),

I agree fully that algae aren't limited by nutrient starvation. I also agree fully that they exist in a quite distinct environmental niche. I think most people would agree that if the plants are growing nicely that algae will generally not get a foothold. Your observations regarding NH4 seem to make sense - very few serious aquascapers use heavily stocked tanks. I'm pretty sure this isn't just a coincidence.

I'm still stuck on a very fundamental question:

Our tanks, without exception, provide algae with every single thing they need. Light, CO2, and every possible nutrient is provided in mega-quantities. This should fulfill their every need. They should be in absolute algae nirvana. If I were to take all the plants out of my tank and maintain the light and nutrient levels exactly where they are, the algae would go crazy. Somehow, adding plants to the equation kills / inhibits the algae, even in my hopelessly overstocked tank.

I don't want to beat an old idea to death, but isn't it possible that some form of chemical warfare (allelopathy, if you want) is ultimately responsible? If you look at the world of microbiology, very minute quantities of substances are secreted by critters to keep other critters out of their turf. One might even say that this is the rule, not the exception. Might this chemical warfare exist in the immediate vicinity of the plant's surface? Healthy leaves don't get algae. If you put it there it dies. Sick leaves are quickly covered. Something is going on there!

I've talked to a lot of people about this. Admittedly, most of them are MD's with microbiology backgrounds, not botanists, but they all reach the same conclusion. Something is inhibiting the algae. This 'magic something' only seems to exist when the plants are really living it up. It seems reasonable (but unproven) to me that plants would be smart enough to create an effective algicide.

A penny for your thoughts........ (I'll paypall it to you ;))
 

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plantbrain said:
If you have stable conditions, then you start to get one or two species that dominate, if you have intermediate distrubances, you get the highest diversity(much like many FW aquatic systems), if you get extreme disturbances, then you get few species. This is basic ecology (See Joe Connell, UCSB)
Tom, just to add to this I've seen the same analysis done on marine reefs. It seems there exists an intermediate level of nutrition where biodiversity peaks. Below that level of nutrients, you effectively have a desert and sparse growth, above that level one tends to get large mono-specific colonies. Only at intermediate levels (not limiting!) do niches form and biodiversity explodes.

Jeff
 

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I'm not proposing that there is a chemical that the plants secrete into the water column. The dilution factor would require the plants to make pretty large quantities and you're right - activated carbon would easily remove it. How about a substance that remains on or acts very near to the leaf surface? Penicillin mold doesn't kill bacteria across the room, only those in very close proximity.

I'm not proposing that I have proof of it's existence. I'm only suggesting that there may be a straightforward explanation that hasn't been described yet. I think almost anyone would readily admit that there is much about this process that we don't quite understand yet.

plantbrain said:
You mention very strong inhibitors, needed in minute amounts.........well, if they where that strong, why has no one ever seen this in natural systems even once?
I've certainly not read the original article, and I really should be smart enough to keep my arguments within my own realm of expertise, but there is some interesting info on Tropica's site. They reference a study which shows that Myriophyllum species produce Tellimagrandin, a phenolic compound that has impressive algicidal properties on blue-green algae. (Gross, E.M., Meyer, H., and Schilling, G. (1996): Release and ecological impact of algicidal hydrolysable polyphenols in Myriophyllum spicatum. Phytochemistry, 41:133-138.)

Does this count as once?

plantbrain said:
How is it that all aquatic plant species exhibit the same lack of algae?
Do they all produce the same intense chemical?
What are the odds that all aquatic plants(even non Aquatics for that matter) produce the same chemical?
You could argue that only plants capable of keeping algae away could have ever become sucessful aquatic species.

plantbrain said:
Healthy actively growing leaves older or younger in terms of the plant?
Time is the issue, most leaves will get crusty(say like some slower growing Anubias, we all know they are more prone to algae) over time, whereas something like Hygro? Stuff grows so fast the algae does not have time to form before being pruned.

Once the new leaves grow above the older leaves, they block a large amount of light. Basically the new growth stays one step ahead of the algae.
There are plenty of people with tanks full of slow-growing species will little or no algae. I don't think that the growth rate of the plants is the reason behind our improved success in keeping algae at bay.

I don't mean to be argumentive - I'd really like to understand what exaclty is behind this. I just don't buy the ecological niche thing. Most things will grow whenever they get a chance. I'd think something as simple as a singe-cell organism with everything to its liking would be happy to grow until limitted by some outside influence.

You say the plants soak up the NH4. Are you proposing that limitting NH4 in the water column deprives the algae of an essential nutrient? This sounds a lot like earlier theories regarding limitting available phosphate.
 

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There is another view.

Stress is something that can stop or suppress survival.

Man becomes sick when he is stressed (lost work, broke car).
Child can sick when stressed (lost mother's attention, lost games).
Plant can sick when stressed (low light, low nutrients, bad temperature).

Simple, algae is disease, no mater what form it has.

Plant can't recover itself. Instead they can change their's generation and make health children. So if you have algae, then first make great environment for plants then change sick plants with new healthy ones, or wait a little until your sick plants make new ones and then remove old.

So EI and PPS simple makes stressless environment for plant.
 
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