So, why does New School = no algae?

I think one important factor is the types of algae growing. In most cases (except for cyanobacteria) algae are found in the kingdom protista, a "grab-bag" of organisms that don't fit precisely into the animal or plant kingdom. For example, included in the protista kingdom are multicellular and unicellular organisms, eukaryotic and prokaryotic, and organisms that range from autotrophic to half-autotrophic/half heterotrophic to heterotrophic. Because of this, each variety of algae has entirely different triggers/niches.

This is one of the reasons that I have doubts about allelochemistry playing too large a role in plants' competition with algae. It seems that a plant that is effective at combatting one type of algae would have a hard time with another, as allelochemistry works to block specific enzymes. Of course, the allelochemical could target a single enzyme that is common to all photosynthetic protista, but this seems unlikely IMO when you take the variety of protista into consideration.

Hornwort is the plant about which I have seen the most research relating to allelochemistry. Has anyone noticed whether hornwort combats all algaes equally effectively in a broad range of conditions, or is it more effective against a specific type?

devil's advocate: want to grow algae

hi, i followed a thread from aquaticQuotient to here and find this very fascinating.

i am having algae problems in my 20g planted tank (with fish), so obviously would like to control it.

HOWEVER, i have a dream of growing my own algae: spirulina, and possibly using fishwater as a source of nutrients for the algae tank.

here is my plan so far: i have an empty 35 gallon tank, which i hope to set up as a normal planted fish tank, and grow the spirulina in a separate tank which would also double as a sump for the 35 gallon, thereby cleaning the fishwater while feeding the algae. will it work?

i have no idea what New School, EI or PPS means, but i would like to learn as it sounds like it could help me with my existing algae problem (GSA, BBA and hair) and also allow me to figure out how to optimally grow spirulina algae.

any thoughts, suggestions, reality checks would be great!

lily

OK It looks like this thread is pretty much dead, and I came too late to see anything Tom/plantbrain wrote. I am sorry I missed that. But I'll add a couple comments anyway. Art asked us to play sea cucumber in the beginning of the thread, and I took the bait.

Art, I understood the reason in starting the thread, and you asked a simple and specific question- but I could accuse you of trolling in your own space! (j/k!)

Optimist:

I believe most of you are exactly right; and that it's a combination and balance of nutrient/light competition, and allelopathy. Simple and/or complex, on either end.

I mean allelopathy in a broad sense, which to me may include oxygen levels/redox potentials, where locally regulated by the higher plants, or other "universal" higher plant processes I wouldn't guess at. Complex chemical algicides wouldn't necessarily be the only 'true' allelopathy. Yes, that's fuzzy, overlapping simple competition, but that's how I see it. Interactions overlapping interreactions on a continuum, not anywhere near simple discrete one-cause one-effect systems. I've been out of the hobby for several years, so can't use EI and PPS as specific examples, only maybe as a means of forcibly tipping complex series, or networks, of balances. Oxygen, and maybe peroxidase difference (was that brought up here?), is just the easier example for me.

I said "regulated by the higher plants", because obviously the algae and cyanobacteria are doing the same thing at the metabolic/photosynthetic levels: Redfishbluefish's post (#104) reminds me that chloroplasts (and such) in all organisms are really all various cyanobacteria, evolved as endo-symbionts, as we are symbiotic with our mitochondria*. The biggest difference would seem to me to be sheer mass- it only takes a few higher plants to equal the dry bulk of a tank overgrown with most kinds of algae.

The spirited discussion would be because of each person's variably unilateral approach, weighing one or few parameters as 'the important'. I'm sure it won't be an eternal argument, just insufficient data for now, as mentioned several times already.

* No matter how factual, natural, and logical, it still seems a feels a little creepy thinking about how my minute-by-minute survival, and very existence as a species, is completely under the control of a bacterium in my cells that I am fundamentally unrelated to. Kind of makes the strict idea of Linnaean Kingdoms melt down in my head too. More continuum. In the fourth grade, I read a series of books by by Madeline L'Engle, including A Wind In The Door, involving sentient mitochondria and "farandolae". It influenced and scarred me for life.

And, Pessimist (or skeptic):

Art Giancola wrote:

I remember Kaspar Horst of Dupla thought that Kraus' oxygen theory had been disproved.

Click to expand...

Andrew Cribb wrote:

If there was one magic component (such as your suggestion of oxygen) responsible for slowing or stopping algae growing, it would have been found before now by better equipped researchers.

Click to expand...

The best funded research specifically for aquarium environments would be supported by major aquarium supply companies. If I were CEO, and one of my research teams found that magic bullet, I would lock it up unless or until I could get a profitable product or system out of it, which couldn't very quickly or easily go DIY. Extend that thought however you see fit. Although the explosion of peroxide use probably impacted some algicide sales, I am again not only referring to oxygen, it's just the example quoted.

Redfishbluefish: I don't have an answer on your hornwort question, and haven't grown any in a long time. It was most useful to me to combat diatoms, rather than algaes, possibly through sequestering silicates. But your post reminded me of the whole symbiosis thing. I think I need to have a talk with my endosymbionts, and make sure we're in full accord, before I go to sleep!

Thanks for letting me ramble. My mind has been stagnating the past several weeks, it's outgassing now.

Vincent

This thread started two years ago and we are still not absolutely sure what the correct answer is. However, two more years of experimenting proved again that older the water better. And this comes with fully planted aquarium and very well aerated water. Why is this? A few ideas:

=> Allelopathy produced by plants

=> Water filtration by plant uptake

=> Water aeration - gas equilibrium, 1, 2

Allelopathy produced by plants is real. Higher plants produce minute amounts of momentarily active chemicals to suppress competing organisms like algae.
Water filtration by plant uptake plays a significant role. Plants have the ability to remove almost everything from Gold, Uranium, Sodium to Aluminum leaving water clean. Tap water is not clean and water changes contaminate aquarium again.
Water aeration is a new topic here I would like to introduce. According to Henry's law about solubility of gases we have a problem in aquariums without aeration. Plants are trying to dissolve Oxygen, Fish and denitrification process Nitrogen, etc. and on top of that we are trying to pump CO2 in. It gets out of balance fast and stops working the way we would like it to. By aeration dissolved gases become balanced again where the extra gases escape to atmosphere freeing space for new gases we need, like CO2.

Thank you
Edward

I think this discussion has stepped away from the original question a little too far.

Recently most posts have been discussing cyanobacteria, which is not algae, but instead a photosynthetic bacteria. Applications that relate to plant and algae competition do not necessarily apply to bacteria. I believe that a discussion about cyanobacteria and plant competition belongs in another thread.

In regards to allelopathy. It is my understanding that allelochemicals actually work through bacteria. In this way, if allelopathy were occuring in our tanks, we should actually be looking at the way bacteria and algae compete for the same nutrients.

Also, in response to a comment on hydrogen peroxide. H2O2 kills algae not by raising O2 levels, but by oxidation in the same manner hydrogen peroxide kills bacteria in a wound. Algae is more susceptible to H2O2 treatment because of thinner cell walls than plants. Plants can be killed in the same way if their cell walls are thinner, like mosses or damaged parts of a leaf.

Interestingly on my local forum we have recently been having a discussion on the same topic. Here are my thoughts:

I believe that there is a critical balance between light, CO2, nitrate, phosphate, and traces (I'm including potassium in traces here). When something happens to change the balance algae sense the balance. This tip on the balance tells, or signals to, the algae that this is their time to have the outbreak we all hate.
I don't really believe there is such thing as an algae free tank. All the algae are there, they are just in a dormant phase. When a specific type of algae finds the conditions it likes it goes nuts. Some algae like low phosphate - GSA (green spot algae), some algae like low nutrients - staghorn, and some algae like almost every kind of imbalance we can create.
For each person their is some sort of unique imbalance that they create with their dosing schedule. For me it's GSA. My home tank has plenty of light (4.5 wpg), plenty of ferts, very healthy plants, is mature, hasn't had a water change in almost two months and is doing great with the only exception that every couple of weeks I start seeing typical GSA spots on the glass. My dosing schedule in the show tank at work is conducive to hair algae (I believe this is due to a low N ratio, and in my case it's 'cause the P is too high).
Take an example from nature - algae blooms often happen in streams and lakes where runoff from fertilized farms contaminates the perfect balance. The imbalance usually comes from phosphates. An algae bloom results.

So, to sum things up a bit...I believe the best way to keep algae at bay is to simply keep a proper ratio of light, CO2, macros and traces.

A great thread!!.

I take it that after 3 years or so of this thread running that there isn't a simple definitive answer?

I have been keeping planted tanks on and off for the last 15 years with varying degrees of success and fighting what has seemed at times a losing battle with algae.

But that is nothing, plants and algae have been slugging it out for the last few 100 millions years. Higher plants I would say have broadly won the battle for
the well lit and
well nourished niche because when we provide these conditions they thrive and algae does not but when things are 'out of balance' then algae thrive.

When ever you see this type of competition evolve however in nature you often see a multitude of adaptations and strategies by both sides, if it was just one simple mechanism
that plants or algae use to dominate an ecosystem then it would have only been a matter of time before a counter strategy evolved - examples of this are antibiotics produced by fungi and enzymes produced bacteria that deactivate the antibiotic - it's a kind of arms race.

I think allelochemicals do play a role but I don't know how important they are. People that do large weekly water changes and use activated carbon would surely
be removing them all the time but I never see people complaining that they had an algae outbreak when they added activated carbon to filters.

In a broader sense though I think allelopathy is still the key, you seem to either get good plant or good algae growth and not both together. Even in well fertilized tanks where there are plenty of nutrients, there should be plenty of nutrients for both algae and plants but either one or the other thrives not both (by thriving I mean actively growing because you can as we all know get a well planted tank that is taken over by algae).

So if allelopathy does exist [whatever the mechanism], then this implies that even in a well lit and well nourished tank that plants and algae are still fighting over some vital conponent that is limiting.

The only thing I can think of is CO2, and even with extra CO2 injection I would say that CO2 is limiting, just not as limiting as a tank without added CO2.

Diana Walstead in her book explains that CO2 concentration is quite often many times higher in aquatic systems than surrounding air but that does not compensate for the fact that C02 diffuses thousands of times slower in water than air (I'm trying to remember the details of her CO2 chapter of the top of my head).

As far as I understand vallis is one of the aquatic plants that can use bicarbonates, in my tank that uses the el natural method, CO2 is probably limiting. I have noticed that when I removed most of the vallis I was able to get better growth from other plants and a more diverse range of plants. The vallis I assume, is encouraging the conversion of disolved CO2 to bicarbonates to replace the bicarbonates it has removed thus removing CO2 and making less available for plants do no use bicarbonates. The effect is lessened when you add extra CO2 or trim the vallis back. At least that is my observation.

My observation of vallis growth may not be an example of allelopathy but perhaps shows that a slight advantage one plant has over another plant or algae can make a big difference to its success in a fish tank. Perhaps as well a slight advantage provided by allelochemicals is enough to tip the balance for either plants or algae for the continuing battle to get enough CO2.

These are just my thoughts I'm not an expert and will probably change my mind by next month but it is a fascinating subject.

Yeah, I think this is perhaps the single best question ever posed here at APC. Certainly "the answer" is not a simple one.

My own thoughts about allelopathy have shifted a bit since this thread started. People like Tom Barr will adamantly state that this does not play a significant role. When I see algae in my aquarium, it generally shows up on older, unhealthy portions of the plant. I doubt that waterborne allelopathy has much effect. I do think that there's a possibility that "plant defenses" might be active within a local area in healthy plant tissue. Plants don't have an adaptive immune system in the classic sense but they do employ innate systems of immunity. It's possible that they can deploy proteins or protective barriers on their surfaces that prohibit the growth of certain other organisms. Unhealthy plant tissue would therefore be unable to resist algae colonization.

Certainly there is much more to the picture. It's pretty clear that certain algae "watch" for environmental clues that tell them that it's a good time to activate, grow, and reproduce. Avoiding these activating factors is probably a big part of the soultion.

I proposed this question to one of my professors (Horticulture Phd, specializes in Floriculture) and he suggested allelopathy. There is very little research on the subject and not nearly enough for anyone to have a complete understanding, especially in aquatic environments. We know that a lot of large canopy trees will 'poisen' the ground under them with leaf litter and chemicals that are released as the leaves decompose. This frees more nutrients for their roots and keeps other trees from growing into their canopy and shading them.
Now there is proof that allelopathic chemicals exist, and it is a pretty sound theory, he is an intelligent guy. Algae can use No3, po4, and whatever so obviously in the case of EI (I am so far unfamiliar with PPS) the algae should be growing. In an empty take with lots of light and these chemicals (In ANY RATIO, the ratio is not important to algae and plants) we expect to see algae. Therefore something about the presence of healthy higher plants prevents excessive algal growth. I think of algae as a scavanger, it will take in nutrients down to the part per BILLION, and is more efficent than higher plants and living off low levels of nutreints (Although probably wont be prolific at low levels).
I dont think we can answer this question, but we can make some educated guesses. I'm still in college trying to figure things like this out... maybe one day i will have a better answer haha.