[plantbrain]

Originally Posted by @tom

Hi
>> Food in, plant growth out. <<

This way is still growth limited by the amount of TE's that comes from the food.

Depends on the plant's growtrh rates, if limited with low light, no CO2 additions, it can supply the needed nutrient demands for months, years even.
Substrate sources can provide this since the amounts of TE are very small, while a nutrient like NO3 is very large and the substrate source might run out after a month.
Fish waste alone cannot supply a high light tank with CO2 and dense plantings.
You'll get algae due to NH4 not being cycled fasted enough=> leads to algae blooms.

You can test that fairly easily.

Many tanks run that way, and I don't feel the need for speed.

I think the proper question is how fast do you wish to grow the plants?
I use 3 basic groupings: Slow, medium and fast.

Slow: non CO2, low maintenance, nio water changes, general neglect, tanks look quite good, fish health is good, the plant health is not 100%, but that's not the goal here, decent looking tanks can and are acheived, it requires patience.
Medium: Low light still, but with rich CO2.
Dosing/water changes are done weekly, slower gerowth, easy to grow any plant, light slows the growth rates down, thus the uptake, there is a lot of wiggle room with routines and dosing here since the uptake is slowed down and the plants do not suffer right away.
Good for most folks over the long term.
High light: great for gardeners and scapers wanting to have dense growth and to prune and grow plants fast.

Comparing this, with your EI / armano style of planted tank running is useless.

No, not really, Amano and myself use both high and low light approaches and use them effectively to reduce dosing and pruning issues.
Many Europeans use less light than folks in NA. That allows more wiggle room with differnt dosing routines.

When you add more light, you quickly find that many of the routine that worked at lower light, now give you trouble.

Reliance on fish food declines as you add more and more light and you must add inorganic forms of N, such as KNO3, as NH4 forms will cause algal blooms.
NO3 is far more benign than NH4.
As loing as the NH4 is maintained at very low levels(in = out) things work well and for the same reason reagding algae control and plant health.

If you unbalance these, you will get algae or plant deficicency issues.
That's the balanced part

It's all about rate and what rate you desire for your given goal and routine and habits.

The Amano style and the EI both work at high abnd low light ans can still be done well at any of these lighting/methods, even non CO2.

I've done 2 non CO2 planted tanks with no fish.
It was fairly easy to maintain nutrient level at very low dosings 2x a week using inorganic nutrients. I did water changes once every 3-4 months after a pruning.

Simple thinking by me : light W/gal x 10 = co2 level

The point is to decompose N, C and P by using the right c:n ratio without losing it to sediment or filter uptake by
regulating the amounts of heterotrophic and nitrifying bacteria.

Removing a biological section of the filter means you simply allow more NH4 to use used rather than having it convert to NO3........the amount of N is still the same.......the bacteria population only regulate the FORM of N, not the export/import.......... the amounts of C used by the bacteria from food is rather small in the overall CO2 demand and import/export of CO2 with the air above.

In highly productive areas where there is a large amount of organic material accumulation occuring, like a nasty swamp, then a fair amount of CO2 can come from these sediments, but our tanks are not very rich by comparison.

This info is about http://www.iwaponline.com/wst/03101/wst031010195.htm denitrifying.

You need to be specific with this, all I get is a listing or journals. Therer are many denitrying studies done on wetlands and bogs.
Do these apply to your tanks? Do we weed and add fish food to these natural systems? What are the organic matter loading rates in these systems?
The OM loading rates are much higher than our tanks.

This is easily testable.......
Remove the plants, add only NO3 as a source.......see how much is removed, the amount without the plants removed will be lower since the plants pump O2 in the substrate and reduces the denitritying bacterial regions.

Measure how much loss of NO3 you obtain over a week's time, then add the plants back and allow them a couple of week to grow in and measure this difference.

The NO3 removal is very low relative to the plant's uptake.
That also does not include the NH4 removal plants also do.

I know wetland denification is well explained in Aquapalnta and Reef Art. I made a detailed diagram of all of the N cycling processes that occur in a submersed wetland soil.

Wetlands can become Carbon limited in some cases: Reddy, White have done a fair amount of research on this issue. See this thread for more on C:N issues and food. Many reef folks limit their food way down.

http://reefcentral.com/forums/showth...postid=4135659

The FSF is used for it's thin biofilms and creating the still needed no2.
Filters are never to be stopped..

Yes, but with routine pruning, these films are minimized, with good plant, they are also minimized as well. Algae and other eipihytes also form in these thin film spaces.

Water changes ( 25% / 2 weeks RO water ) is done only to prevent inhibition / toxicity.

Okay, like what might be toxic or inhibit growth......eg what specific level of something is required for this to occur??
I've gone years without a water change, I have friends, that have 2-3 years without one.............N is low..........fish breed etc............
Again, it gets back to rate, the faster youm go, the more issues you will have with things running out nutrients, rather thann toxic effects from build up.
Espeically when all you rely on is food alone.

You can rely a fair amount on food with low light, but topping it off with some inorganic macros will improve the plant's health and make the tank look better. Balancing food for the plant's health is not perfect, there are trade offs..............

Plants will also have that effect.

What effect? Allelopathic? I don't think so, this is easy to test for.............here we go again...........
Add carbon, carbon will remove any allelopathic compound, this is the standard control for aalelopathic compunds done in research.
Additionally, allelopathy has never been shown in the field in any aquatic plant on algae or another plants ever to date.............
Additonally, allelopathic compound produced by all 300 or so aquatic plants species all produce the same effect and the same intensity on algae?
What are th eodds of this ocurring?
I'll tell, you none. Well perhaps a few trillion to one

[quote]Ca release from the food also increases the kh slowly. ( Low Kh )
Ca will also bind to P and Fe ..[quote]

The Ca released from food goes right to the plant. Ca will not raise KH, KH is HCO3, in planted tank without water chnages and CO2 additions, the KH goes down due to bicarbonate usage when the tank becomes CO2 limited.
Ca will bind to PO4 and but to Fe? PO4 ansd Fe will bind....but I'm not sure how you plan on binding Fe3+ to Ca2+.
In any event, they(Ca and PO4 or PO4 and Fe) can form in the oxidized water column, then be reduced into their ions in the substrate or by the roots themselves, plants and the substrate are not static, the nutrients do get cycled.

The redfield ratio has been debated since release on many forums.

That conclusion is incorrect and heThe guy who has the site) would have a difficult time backing it up for FW applications. The reasoning is flawed and the application is wrong. It's not a marine phytoplankton nutrient limited system. It compares apples to oranges. You can try to do that, but I do not agree with that illogical conclusion.

It also does not make sense in practical terms, I've done the opposite of some of those same conclusions and had quite the opposite effect.
I had excellent plant growth, not algae. I can repeat those experiments and so can(have) others(for many years).