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Why does EI in high light tank not cause algae?

B

Barney

Seedling
Joined
29 Jul 2007
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14
I know for a fact that high doses of phosphate and nitrate in a heavily planted, well lit CO2 enriched tank do not cause algae issues. The thing I'm curious about is why?

From what I have read everyone says that in a high light setup as long as you have plenty of ferts (EI for example) and plenty of CO2 algae wont grow. The thing I don't understand is why? logic would seem to say that if you are dosing more than the plants can use then the left over is going to get used by algae? I know this isn't the case though from my own experience.

The reason I'm trying to understand this is I have a marine reef tank as well. Everyone who has planted tanks says that phosphates do not cause algae but in my reef tank as soon as my phosphates start rising I always get an algae outbreak (and know its time to replace the phosphate remover).

Does it just work different in a marine environment? Obviously the reef tank doesn't have plants but in an EI planted tank its not the plants using all the nutrients that is stopping the algae (as they are dosed to be in surplus) so is it the plants themselves that stop algae growth?
 
plants can utilise the nutrients before algae can appear and use them.
 
Thats the bit I dont get though.

In an EI tank isnt the point that all nutrients are supplied over and above the plants requirements so that they always have a constant supply of everything (meaning there is surplus in the water column)? I might have just missed the point completely though :)
 
Barney said:
Thats the bit I dont get though.

In an EI tank isnt the point that all nutrients are supplied over and above the plants requirements so that they always have a constant supply of everything (meaning there is surplus in the water column)? I might have just missed the point completely though :)
Click to expand...

im not into it all that much to know the science of everything, however i am intrested.. Clive(ceg) may see this later, he is the best one to talk to.
 
there are 2 stages of algae, first is algae spores and second is the flagellate form. the algae spore seeks out a combination of light and amonia to then turn in to the flagellate (which is what we see as the visable algae) this flagellate seeks a different quary, this flagellate form feeds on nutrients and ferts.

i learnt from this thread, and mainly cegs awnser about 3 awnsers down.
http://ukaps.org/forum/viewtopic.php?f=11&t=3217
 
Thanks :) it was his post that got me thinking about it:
viewtopic.php?f=34&t=1211

According to this the maximum possible uptake in a planted tank with unlimited light is:
Nitrate (NO3) 20ppm per week.
Potassium (K) 30ppm per week.
Phosphate (PO4) 3ppm per week
Magnesium (Mg) 10ppm per week
Iron (Fe) 0.5ppm per week

This is in a tank with unlimited light. According to the above post these are the levels to shoot for which means that unless you are running 5-6wpg of light there is always going to be plenty of all of the above floating around in the water column.

Now in a non planted marine tank I can tell you that 3ppm of phosphate will cause a huge algae outbreak (even with no detectable ammonia and little to no nitrate). It can be shown that it is the phosphate as once you add phosphate remover and the phosphate levels fall again the algae goes away.

Edit: thanks Glen and Aaaron who posted while I was replying. Will read through now :)
 
glenn said:
i learnt from this thread, and mainly cegs awnser about 3 awnsers down.
http://ukaps.org/forum/viewtopic.php?f=11&t=3217
Click to expand...

Interesting! According to the answer it is ammonia that causes a bloom (at least in FW planted tanks). The next question is what level of ammonia is enough to cause this?

Also in a marine environment this doesnt seem to tie in as a rising level of phosphate would cause an algae bloom? Unless of course the phosphate just feeds small amounts of "mature" algae which is always present in the tank and causes it to spread, though in theory the same would then happen in a planted tank?

Just trying to put it all together in my head really as in the reef keeping world algae problems are always put down to phosphates (which in my own experience appears to be true) but in the planted tank phosphate levels can be high and there is still no algae outbreaks (assuming everything else is present for good plant growth).

So either something is different between the marine and FW environment or there is something else going on?

(PS I'm not talking from any scientific viewpoint, just from my personal experiences so I'm probably way off or missing something obvious :) ).
 
Barney said:
I know for a fact that high doses of phosphate and nitrate in a heavily planted, well lit CO2 enriched tank do not cause algae issues. The thing I'm curious about is why?

From what I have read everyone says that in a high light setup as long as you have plenty of ferts (EI for example) and plenty of CO2 algae wont grow. The thing I don't understand is why? logic would seem to say that if you are dosing more than the plants can use then the left over is going to get used by algae? I know this isn't the case though from my own experience.

The reason I'm trying to understand this is I have a marine reef tank as well. Everyone who has planted tanks says that phosphates do not cause algae but in my reef tank as soon as my phosphates start rising I always get an algae outbreak (and know its time to replace the phosphate remover).

Does it just work different in a marine environment? Obviously the reef tank doesn't have plants but in an EI planted tank its not the plants using all the nutrients that is stopping the algae (as they are dosed to be in surplus) so is it the plants themselves that stop algae growth?
Click to expand...

A marine system is much more stable than any FW environment.
Subtle changes means seasonal changes there and a good time to change gears.

In FW systems, this same thing can and does occur.
Runoff from flooding, spring rains/snow, water level changes, temps, light etc all affect things, same for many marine systems also but to a lesser degree.

Reefs are not marine planted systems.

They are very different.

Marine plants live in shallow richer nutrient systems, and soft rich sediments.
Like FW plants.............

They like high nutrients much like FW plants, but diatom blooms are an issue above about 0.4ppm of PO4 from KH2PO4.

In FW systems, just like an established forest, weeds(or algae for us) cannot grow even though there's plenty of soil nutrients. If you remove all the trees and forest, then the weeds will thrive.

What is the control there?

Sort of the same for FW aquatic systems. The plants act like the forest does.
But you have have good conditions for the forest to grow and you have to establish the forest before the weeds can take over and prevent new growth. I'm leaving some things out, but it's basically the same type of thing.

Aquatic plants, where well established, define the system when the % surface area of coverage is 30-50% or more, not nutrients. Algae likely do not grow as they are able to take advantage seasonally of larger changes, perhaps in NH4, light, CO2 etc as signals, much like spring rains and warmer weather signal growth of annuals in higher plants. Why do we have more than one type of algae? More than one type of aquatic plant?

They are better able, at a cost, certain conditions that others are not.

NH4 alone is not the inducer, it can be but if the light is limiting, then what? You can have high NH4 and no algae bloom.
Likewise, CO2 can be all over and no bloom if the light is too low.
If you go the other way, crank the light but not CO2, and add high NH4.......well.
That's different. But then the plants/algae are no longer equal, one is limited, the other is not and can grow very fast.

The other thing is how the tank is doing prior to treatment.
If the plants are already stressed, poor CO2 etc, stunted, some algae, and you try and compare a treatment to a tank where everything is doing well, they are not equal/comparable.

Regards,
Tom Barr
 
Thanks for that Tom. After reading that it makes a lot more sense and if I had thought about it in the right way I should have come to the same conclusion. As you say marine environments are incredibly stable so life has adapted to this and small changes in water chemistry can trigger big changes in the marine life.
 
Hi all,
I'd have a slightly different take on this, that would have a "pick and mix" from the other answers. It would be that in the freshwater aquarium the balanced combination of high CO2, high nutrients and PAR leads to very fast higher plant growth rate, and this means that the relatively slow growing algae are exported during filtration, tank cleaning and pruning, and it appears there are no algae. I would strongly suspect that all tanks actually have all stages (sporophyte, gametophyte etc.) of the various "algae", "blue-green", Cyanobacteria, "green algae" - Chlorophyta, "red algae" - Rhodophyta etc present, and that their growth rate/germination rate/growth form is stimulated by the additional resources (assuming that at least one parameter was limiting), but that this effect is dwarfed by the increase in growth rate of many of the higher plants.

In the marine situation there are coralline algae etc that are adapted to stable, low nutrient conditions and have a low maximum growth rate, and also potentially much faster growing opportunistic diatoms, phytoplankton, sedentary green algae etc that are stimulated by extra nutrients, in the case of your marine tank you can say that these opportunistic algae are definitely phosphate limited. You have a very clear feed-back system, low P - low levels of algae. You also probably have a much more complex ecosystem, with many more organisms feeding on the different algal life stages, and probably a lot of structure that isn't cleaned by the owner - "living rock", coralline encrusted surface etc. for the algae to colonise.

As an example many of the "bare" rock surfaces, in Milford Haven Pemrokeshire, grew abundant green algae in the aftermath of the "Sea Empress" oil spill, this was because the death of the grazing molluscs, and particularly Limpets (Patella spp.), as the Limpets returned the coverage of the green algae rose. The Limpet grazing was the major factor in preserving the green algae free rocks, (also shown under controlled experimental conditions by excluding grazers with physical barriers) in more exposed conditions it is the degree of wave exposure that limits algal growth, and grazing is irrelevant, in both cases nutrients are largely irrelevant. If you went to an area of the Mediterranean sea where the were very little in the way marine currents or inflow of terrestrial nutrients, you would find shallow water rocky areas with very low biomass present, these situations really are nutrient limited.

There are also allelopathic effects as they are going to be very difficult to quantify, although certainly in the marine situation many of the sedentary organisms will be actively attacking their neighbours as well as competing for light, nutrients, food etc.

I've got plenty of scientific references if any-one is interested.

cheers Darrel
 
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