@tom said:
Well I agree , with you Tom that P is often a limiting factor.
But using our feeding method will free up all plantnutrients accept K.
Well, you have to add enough of the nutrients in a balanced ratio for a given growth rate otherwise this will not be true.Carbon is
not part of this equation in terms of __plant growth__ which is what I stated previously.
Carbon as an electron donor can be limiting in some soils with little organic content, eg the bacteria are carbon limited, this is not the same as "CO2" limited. Plants are never carbon limited in this senmse, they are autotrophes, wereas the bacteria in the referenced paper are heterotrophes.
@tom said:
The proces consist of 2 steps that, when combinend result in lower needs of plantnutrients.
I am not clear what you are are saying here. You get the same plant growth with less nutrients? The nutrients still need to come from somewhere ansd the rates of plant growth are directly related, there is no way around a simple 2 box model, what goes in MUST come out.
Food in, plant growth out.
@tom said:
First, you slowly change from your current fishfood source to using frozen food species
with a low C - N ratio such as Mysis and Bosmina.
This will result in faster and total microbial decomposition.
So your bottem becomes cleaner and higher amounts of elements can be used by your plants.
Well this is bacterial decomposition/remineralization. A good substrate, filter, water changes etc will facilitate that. Carbon can be limiting to the bacteria in a
NEW tank, I suggest adding some peat and mulm from an established tank for this precise reason, the bacteria need some carbon to live on, new tanks are often
lacking. But in an established tank, carbon is non limiting as the bacteria play a decreased role since the plants use up the nutrients. All the bacteria are doing for you then is taking bound organic carbon and oxidizing it to CO2.
Which is my point in my last post.
The N is going to be used up by the plants once the fish excrete the waste as NH4+.
Plants will not use the Carbon, they will use some of the CO2 once the bacteria cycle it.
See if you can measure any NH4 in a well run plant tank.
@tom said:
It's research I'm very familar with, I've studied this precise topic in depth at UF in grad school with the top person in the world in biogeochemistry in wetland soils, Dr Reddy.
Your
application of this research is what I'm questioning here.
The fish waste is a very labile form of DOC, plants are not DOC limited. bacteria can be. As you increase DOC and POC, this places a strain on the O2 levels, these increased cycling rates by these heterotrophic bacteric also directly correspond to an increase in O2 consumption as they oxidize the DOC into CO2.
But bacteria play minor roles in planted tanks, the main player is the plants as far as N is concerned.
Algae and plants are not Carbon, DOC limited. They might be CO2 limited.
Adding a different C ratio of food, eg, high Carbonhydrates migth help the bacteria population grow, that might help NH4 removal, but plants are much better in general at removal of NH4.
But a good bacterial colony is a good backup should you neglect your plant's needs, but so is a decent filter

I do not think the role of bacteria and Carbon is significant as you contend and you have not offered any compelling evidence to suggest otherwise in the research nor observational.
@tom said:
The second step is in reducing our filtermaterial.
Biofilms in filters take up huge amouts of nitrates and TE's for there metabolism.
So how much TE and NO3 do aerobic bacteria in the filters are use up?
Please tell me how a filter that is aerboic with redox values at 350-500mv is able to reduce NO3 to N2 gas?The denitrifiyers neeed a range of redox values around 200-300mv This may occur in the substrate, but not in the filter in any significant way. This is easily testable by an aquarist with a good set of kits.
See how much NO3 is removed by removing the plants and letting the filter remove it.
I think you will quickly see that it doesn't do much

This is common sense, not technical science.
@tom said:
So we got ride of all filtermaterial and simply use them for only heating, co2 addition and water flow.
However some plants simply will not grow if there are no nitrates.
So you'll have to add a fluid-sand-filter for this purpuse.
FSF are poor filters IME and IMO.If they stop running for 15 minutes or more, their colonies die off fast. Also, adding filtration only changes the NH4 to NO3, you first need to have NH4 to begin with, in planted tanks I have not measured any NH4, it's used up by the plants as fast as it's produced.
We have done some tracer enrichment studies with N15 and I plan on doing some here at UC Davis with radioactive N rather than mass spect type work.
@tom said:
The only element that can't be found in this fishfood is Potassium so
that's all you need to add extra.
All basic rules for a planted aquarium still have to followed.
So you will still have to add co2, plenty of light, regular
water changes and have a low KH.
Why a low KH? I do great at high KH's, research both in natural systrems and in lab studies show plants do better in higher KH's. There are relatively few exceptions(1% of the commonly kept aquatic species), but even those will grow.
Also, water changes: thius removes N and C each time, therefore the role of the bacteria is
GREATLY reduced in decomposition's role.
Your exporting all the C and N from this system which was your original premise. This nulls your entire argument.
@tom said:
Most research into this stuff has been done by leading dutch biochemist Adriaan Briene.
Before this he also studied the Redfield ratio ( N - P ratio )
His pages are in dutch but can be found here.
http://members.lycos.nl/brieneoord/aqua/zooplankton.html
and here
http://www.xs4all.nl/~buddendo/aquarium/redfield_eng.htm
Give it a try, and you'll see some amazing results.
Greetings
Okay, this guy, I keep hearing this Redfield ratio pop up from the Dutch sites.
There is a problem with this concept and notion and I've argued it into the ground several times with no real response back that had any merit.
Redfield ratio deals with nutrient limited open ocean phytoplankton. Aquatic plants are radically different and totally different in terms of a niche. They also possess different ratios, roughly7 10: N

ratios, FW algae, about 14:1 on average if you review the relevant research on specific FW plants and algae. I've done that.
The other issue with the Buddy ratio and that whole mess: it assume you can limit the algae through ratios and such, those references are for marine phytoplankton algae, not FW systems. The other issues: aquatic plants and small algae are not even in the same niche and therefore do not compete for the same resources, even if they use the same things such as N, the scale at which they become limiting are enormously different.
It's like suggesting mice and elephants are in the same ecological niche, again common sense says otherwise.
Science is useful, how you apply it and accept it is another matter.
Bringing up the DOC issue is good, we had suggested adding glucose to the water to amplify the bacterial growth as this is gone in research for studies on carbon bacteria limitations. We discussed this years ago on the APD in more detail as it applied to planted tank, Neithe rI nor Roger Miller found an effect.
I have a hard time seeing that it would for the reasons stated here as I have not been able to show that is did anything on a more practical and controlled manner for planted tanks.
Then the food source does not matter and this allows you independent control of things like C and N and K etc in a planted tank or a wetland or a growth chamber etc.
My critque here is not personal, but the arguements present do not make much sense based on the research and the application. To the average aquarsit without a background in biogeochemistry of wetlands, they might certainly seem convincing though
But it's specificaly what I do for a career and hobby, not many are that lucky.
If you are inteersted in knowing more about DOC/POC and carbon's role, and a ton of references on this subject, I will have an article coming out on the
www.BarrReport covering Carbon in great detail.
This(carbon) is the core of biogeochemistry in wetland soils and is heavily studied in the USA in Florida.
Regards,
Tom Barr