# Growing plants in tanks with heavy bio filtering?



## RedDelPaPa (May 18, 2005)

Hi all.

New to this forum, but not so new to the world of fishkeeping and growing aquatic plants.

I just wanted to share my successful and unsucessful experiences in growing aquatic plants.

Over the years, I believe I have discovered a link between heavy biological filtering and unsuccesful attempts at growing aquatic plants. For years, I have kept Hornwort, Val, Sag, and Hygro Polysperma. All these plants mentioned seem to do quite well in my aquariums, and my Dad's alike. However, if introduced into an identical setup(lighting, fish, substrate), only with an undergravel filter, plant growth almost completely stops, and in some cases, dies completely. I have heard stories that the cause is the UGF is keeping the plant roots from absorbing nutrients, and trace elements from the gravel. I don't think I buy this theory because of the negative affects it has on the floating plants as well. Like the Hornwort.

Over the years I have come to strongly believe that the plants require small amounts of ammonia in the water in order to grow. Possibly even Nitrite's too. After all, garden fertilizers contain ammonia. And I think heavy bio filtering takes away the ammonia before the plants get a chance to use it. Thus causing stunting or eventual death of the plant(s).

What are your thoughts on this?

Thanks for any info,
Nate


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## Laith (Sep 4, 2004)

I haven't seen a UGF here in any stores in, let's see... in fact, I can't remember ever seeing one anywhere in the region.

Ammonia tends to trigger algae outbreaks. We normally give our plants their Nitrogen through the addition of KNO3 to the tank (Nitrates).

In a way you're right in that if the plants have no source of Nitrogen, they will do very badly. Once again, that's why we add KNO3 to planted tanks.

Biological filtering is less important in a heavily planted tank which is why when I set up a tank heavily planted from day one I never get a cycle.


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## Laith (Sep 4, 2004)

And welcome to APC!


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## RedDelPaPa (May 18, 2005)

Hello, and thanks for the welcome.

Can anyone explain then what is happening to the water chemistry in a tank with heavy bio filtering, that would cause stunting or death of aquarium plants?

All I can figure is, the heavy biological filtering is taking away some sort of nutrient(s) that the plants need in order to grow.

I believe that nitrate deficiency would never be a problem in a tank with a heavy to moderate fish stock. Especially in a tank with heavy bio filtering. Nitrate supply in a setup like that should be through the roof.


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## SnakeIce (May 9, 2005)

The Undergravel filter only tank has enough nutrients, but the flow of water in the tank isn't enough to disturb the boundary layer that surrounds solid surfaces and thus your plants use up all the nutrients in the water close to them. They then don't grow even though there is nutrients in the general tank water.


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## Raul-7 (Feb 4, 2004)

RedDelPaPa said:


> Hello, and thanks for the welcome.
> 
> Can anyone explain then what is happening to the water chemistry in a tank with heavy bio filtering, that would cause stunting or death of aquarium plants?
> 
> ...


It is true that bio-filters produce a lot of NO3, but remember they do this by converting ammonia to nitirite and finally nitrite to nitrate. Plants can use all three as a source for nitrogen, but ammonia is the preffered nitrogen source. Thus the plants will compete with the bacteria for ammonia, plants will eventually get the upperhand and the bacteria colony will begin to die back.

Plants alone can keep ammonia under control, but for this to happen you need well-established, healthy growing plants. The reason why we get an algae break when we setup a new tank is because the plants aren't well-established, and algae end up getting the upperhand during the break-in period. Algae diminshes once plants flourish.

I'm not saying you don't need one, we all need them as backup incase our plants aren't doing great. You just don't need something like a FBF, Wet-Dry, etc. After all bacteria is everywhere in the tank, and plants aren't at all affected by that. In fact we need both, plants and bacteria, to sustain a healthy aquatic environment.


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## Phil Edwards (Jan 22, 2004)

If you have a UGF in your tank I would recommend finding a powerhead small enough to fit on it and use that instead of an airstone/bubble-lift mechanism. Your filter plate and substrate should have trapped enough mulm to provide enough NO3 to the plants. Adding a powerhead to get good current will only help deliver that to the rest of the system. 

Best,
Phil


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## Simpte 27 (Jul 16, 2004)

I don't see the direct relation between the heavy bio-filtering and poor plant growth. The bacterial colony that dwells in the gravel does get first crack at the ammonia and nitrites but their finished product is a macro fert (NO3). I would tend to think that the problem is something else. Could be the UGF is stunting the roots but I couldn't tell you for sure. Plants don't need ammonia. If they did why don't we dose it?


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## RedDelPaPa (May 18, 2005)

Simpte 27 said:


> I don't see the direct relation between the heavy bio-filtering and poor plant growth. The bacterial colony that dwells in the gravel does get first crack at the ammonia and nitrites but their finished product is a macro fert (NO3). I would tend to think that the problem is something else. Could be the UGF is stunting the roots but I couldn't tell you for sure. Plants don't need ammonia. If they did why don't we dose it?


Well, you do, on your lawn. And a plant is a plant. Probably not in the aquarium because it's toxic to the fish. And I don't think the UGF is stunting any roots on the hornwort, but it does still affect it negatively.

I'm telling ya, they do need ammonia. And like the gentlemen above said about ammonia being the preferred nitrogen source, I believe it. It makes perfect sense from the experiences I've had. From the 15 years of trial and error between both my Dad and I, there is something to this. Something that I don't think is completely understood yet. Even by so called "experts".

I'm telling you. For example, my Dad has a nice 30gal tank with a moderate fish load. It has an undergravel filter in place, but not in service. The tank is well planted with atleast half being occupied by many beautiful bunches of Giant Hygrophila, and a nice sized bunch of floating hornwort. Once a month, he has to throw away a big mess of hornwort, and trim 6 or 7" off the Giant Hygrophila. So I would say the plants are doing well. Nice and pretty green. Not a dead or decaying leaf on them. Fire up the UGF, and within a week or 2, all the plants stunt and starting turning yellow. Even beginning to rot away. Leave the UGF running long enough, and their won't be a living plant in the tank before long. We've seen this happen a half dozen times before.

So without a doubt, I'm pointing my finger at the extra bio filtering the UGF provides.


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## shalu (Oct 1, 2004)

UGF is not more effecient biological filter than wet/dry, now is it? And I have no problem growing plants with a wet/dry filter with a sump.


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## Laith (Sep 4, 2004)

Yes, I've seen tanks with large very efficient (non-UGF) biofilters running and beautifully heavily planted, not a rotting plant in sight.

Plants will not rot if there is no ammonia as long as nitrates are present. Plants *do* suck up nitrates like crazy. I have cannister filters running biofilter material on my planted tanks and only see problems when the Nitrate levels bottom out. In that situation there is not a sufficient Nitrogen source from anywhere and the plants stop growing and eventually wither.


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## Laith (Sep 4, 2004)

Another thought: I've never had a UGF but if it is not running for a significant amount of time and then it's turned on, what exactly is it sucking out from under the plate and throwing back into the aquarium?

I've seen pictures of people tearing down tanks with a UGF and it's not a pretty sight when they lift that plate up. Maybe something accumulates under there when the UGF is turned off after running for awhile and this stuff is thrown back into the tank when its turned back on?

Just an idea...


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## RedDelPaPa (May 18, 2005)

Laith said:


> Another thought: I've never had a UGF but if it is not running for a significant amount of time and then it's turned on, what exactly is it sucking out from under the plate and throwing back into the aquarium?
> 
> I've seen pictures of people tearing down tanks with a UGF and it's not a pretty sight when they lift that plate up. Maybe something accumulates under there when the UGF is turned off after running for awhile and this stuff is thrown back into the tank when its turned back on?
> 
> Just an idea...


Just nitrates. This will happen in an old tank, and in a recently set up tank as well, that's had just enough time to cycle.

In these tanks you mention, are they regularly dosing ferts? Heavy fish load? I wonder if something in the ferts doesn't slowly morph into ammonia after dosing. Causing a burst in plant growth that people see when dosing. Like I mention, I've seen this phenomina happening for the better part of 15 years.

Something else, I've seen a burst in plant growth a few days after a 15 or 20% water change. In an already trace element rich substrate, what is being added or removed from the water that the plants like in this situation?


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## Phil Edwards (Jan 22, 2004)

*RedDelPaPa*,

You're completely right that plants prefer ammonia/ammonium, but in nature as in our, aquariums ammonia/ammonium is very limited. It's quickly consumed by plants and microorganisms. Nitrate is by far the greatest source of nitrogen for plants. Even with artifical supplimentation (fertilization) with an ammonia based fertilizer the NH3/NH4 doesn't hang around long.

Plants don't *need* ammonia, they just prefer it because it's easier to synthesize proteins out of than nitrate. I have a number of aquariums with no fish in them that only gets supplimented with nitrate. The only ammonia available is what little comes from the snails in the tank or from decaying leaves. Both tanks have vigorous growth so I can't believe there is much ammonia available for any length of time.

Regarding the idea that fertilizers are somehow converted to NH3/NH4, that doesn't happen directly. The nitrate has to pass through an organism before it can be made into ammonia again. That's usually accomplished by decay of waste or dead tissues.










Are you using a powerhead to create suction/circulation or air bubbles to create lift in the riser tubes. If you're not supplimenting carbon at all and using an airlift it will blow out any CO2 in excess of what's in the atmosphere. That could easily cause issues with the plants.

Another possibility is that the plants aren't happy with oxygenated water moving that fast around their roots. In nature plants do create an aerobic zone around their roots, but there are important anaerobic processes going on around them. If you make the entire substrate aerobic it's likely that the plants react poorly to that change.

Finally, if you're using any sort of chemical filter in the UGF that will remove a lot of what the plants need to survive. Going yellow and dying after a few weeks sounds a lot like nutrient deprivation to me.

Could you please tell us what, if anything, you're supplimenting your aquarium with? Where do you live? Some areas have high amounts of nitrate in the water supply. For example, European water tends to have 15-20ppm nitrate and high phosphates in it right out of the tap, as do many agricultural regions in the US. That would explain a surge in growth after a water change.

*Laith*,

If a UGF is left off for a while and turned back on it will release all sorts of nasties into the water column. Anything so rich in organic wastes as the mulm under a UFG will produce all sorts of stuff if left in an anaerobic environment for any amount of time. In fact, ammonia is one of the major products of this, along with hydrogen sulfide.

Regards,
Phil


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## RedDelPaPa (May 18, 2005)

Interesting reply Phil.

What could explain the same problem showing its ugly face on the hornwort then? A rootless, floating plant.

I've never had to add external ferts. Never needed them. Plant growth has always been great with a moderate fish load and minimal filtration. What exactly is in these ferts that people are dosing? I know I just laid down some fert on my lawn yesterday, and it's straight up ammonium sulfate. I can't imagine it would be anything different for aquatic plants.

I live in Utah. Where the water is very hard, and the PH is close to 8. It's perfect water for the african cichlids. And it's always done fine for growing plants as well. Out of the tap, our water tests at 0 for pretty much everything except carbonate hardness and permanent hardness.

Running the UGF's doesn't produce any more surface agitation than not running them. So I don't think it's affecting the CO2 content.

Thanks for the reply,
Red


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## plantbrain (Jan 23, 2004)

RedDelPaPa said:


> I'm telling ya, they do need ammonia. And like the gentlemen above said about ammonia being the preferred nitrogen source, I believe it. It makes perfect sense from the experiences I've had. From the 15 years of trial and error between both my Dad and I, there is something to this. Something that I don't think is completely understood yet. Even by so called "experts".


I know a thing or two about NO3 and NH4 as well as urea and overloading tanks with critters to supply the needs of the plants in the tank.

Sorry, every tank can use solely NO3 as the only source for Nitrogen and the tanks do extremely well.

I know this because I have done this test numerous times, this is not anecdotal.

Now if what you say is true, why don't I have any issues?
I'm being specific for the Nitrogen issue, something I have isolated individually.

And no, NH4 is not preferred once you get down to realitistic levels found in our tanks.

It is preferred when these levels are toxic levels for fish. You can see this in the Diana Walstad's book. She did not look at the part of the graph that deals specifically with common NH4 and NO3 levels in our aquariums.

Few, if anyone can measure a NH4 level in a planted tank. 
That's because the plants remove it before you have a chance to measure it.

In a non CO2 tank, this works well.

When you increase nutrient uptake rates and growth rates, you are going to use much more N.

High levels of N will cause algae.
You can test this also.

Add Ammonium chloride or Ammonium sulfate and see. High light/CO2 will respond faster than low light. You'll get the same plant growth rate and lots of algae as well. You can check for info on this in TAG or the APD and other plant related sites.

I have non CO2 tanks with no fish/critters, they are nothing short of awesome. They get no NH4, only KNO3.

You can do it with fish, but I've never seen anything that suggest NH4 is better than NO3 in either non CO2 or CO2 methods.

I think the problem hewre is that you have assumed your rouitne solely changes NH4 to NO3. Plants are affected by many other things than just this choice and you have done a number of things to change that dynamic.

Many folks have dosed both in effort to see this over many years (see APD, and other forums for references) and folks will tell you that adding NH4 will burn you every time. You can add a little, but too much and you'll get algae.



> I'm telling you. For example, my Dad has a nice 30gal tank with a moderate fish load. It has an undergravel filter in place, but not in service. The tank is well planted with atleast half being occupied by many beautiful bunches of Giant Hygrophila, and a nice sized bunch of floating hornwort. Once a month, he has to throw away a big mess of hornwort, and trim 6 or 7" off the Giant Hygrophila. So I would say the plants are doing well. Nice and pretty green. Not a dead or decaying leaf on them. Fire up the UGF, and within a week or 2, all the plants stunt and starting turning yellow. Even beginning to rot away. Leave the UGF running long enough, and their won't be a living plant in the tank before long. We've seen this happen a half dozen times before.


So is it the increased aeration or is it the NH4?
Non CO2 tanks need acclimation time, adding CO2 fools the plant.
Hardy plants can bounce back and respond well(Hornwort is good)
Both algae and plants prefer CO2.
Both these weeds are easy to grow.



> So without a doubt, I'm pointing my finger at the extra bio filtering the UGF provides.


Well, increased circulation, CO2 changes, substrate content/type and a host of other factors including we do not even know what your NO3 or NH4 levels were or were not for each run...............

And I should listen to the anecdotal evidence you provide but you do not even test the NO3 or NH4 levels in this tank?

Have you dosed NH4 or NO3 to see?
No.

You mention that you see better growth after a water change, this is strong support for adding CO2 from the tap and or PO4 and perhaps NO3.

Phil and others have touched upon the Root/aeration issues also.

I think it has more to do with the low light non CO2 method.
Adding aeration tends to make these tanks do poorly.

An easy test for you: add aeration without the UG being hooked up.

Then I think you can rule a few things out.

At a limited slower rate, the plants will use less nutrients. If the plants run out of nutrients, they will melt and die.

If they have enough, then they will grow.
The form of N does not matter. Plants will do fine with either.

I'd rather have slightly slower growth and use something I can test much easier than NH4, and have a much larger long term supply of anyhow.

I'm not suggesting you change what is successful for your routines by getting more light/CO2 testing etc.

I am saying your reasoning has many issues but can be resolved relatively easily by adding an airstone etc to the tank and not using the UG.

I used RFUG's for a decade, they works great.
I also dosed NO3.

Regards, 
Tom Barr


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## Bavarian3 (Oct 21, 2004)

so whats the verdict? Any negative affects to planted tanks with lots of biological filtering (media). I personally have a cannister filled with bio media and another with filter floss. I have a high fish load so i feel its nessecary.


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## RedDelPaPa (May 18, 2005)

Bavarian3 said:


> so whats the verdict? Any negative affects to planted tanks with lots of biological filtering (media). I personally have a cannister filled with bio media and another with filter floss. I have a high fish load so i feel its nessecary.


Well, me and my Dad's 15 years experience says the least amount of biological filtration the better for planted tanks. I do know from our experience, an undergravel filter simply shuts down plant growth. I could take time lapse photos of our tanks and prove it. If someone can positively prove me wrong, please do so. For us, and for everyone else reading this thread.

Thanks,
Red


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## Bavarian3 (Oct 21, 2004)

RedDelPaPa said:


> Well, me and my Dad's 15 years experience says the least amount of biological filtration the better for planted tanks. I do know from our experience, an undergravel filter simply shuts down plant growth. I could take time lapse photos of our tanks and prove it. If someone can positively prove me wrong, please do so. For us, and for everyone else reading this thread.
> 
> Thanks,
> Red


well im only speaking of biological media in the cannister filter not so far as a UGF


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## plantastic (May 23, 2005)

reddelpapa,

The issue that plantbrain brought up about the change in redox potential in the substrate by passing water over it seems to me to be the most likely issue. Plant roots have evolved to function in varying degrees of anaerobic (lack of oxygen) environments. Also the oxygen molecule is practically universal in terms of its effect, chemicaly speaking. So, not only are the roots shocked with a sudden physical disturbance, ie. the moving water, but a total chemical change to the environment surrounding them.


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## Plattykins (Apr 3, 2005)

Hey Red. I looked up this post at your recommendation and I must say that this is one of the most interesting and informative threads I have read here. Your comments and everyone's responses represent the variety of ways in which we have found success in maintaining our planted tanks... or not. I do recall seeing this when you first posted, but at the time, I was on the "no" side of my "yes/no" swing about whether to go filterless. 

I need some time to digest the information posted by everyone, but I will say I believe there is truth in what everyone is saying, including you. It is important to note that we all have a bit different situation, for example, In my case, I do not use a UGF. In any case, the plants will do what they need to in order to survive. Depending on whatever other pieces of the picture exist, whether it be a man-made filter of some sort, frequent water changes, ferts, tap water quality and so on, will determine if the plants are successful.


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## TWood (Dec 9, 2004)

I use a home-made UGF (perforated PVC and a small pump) under plain gravel in my tanks and the plants do fine. I also grow h. difformis in black eggcrate along the back and sides, so to me the gravel becomes just a glorified plant-holder anyway. Crypts do okay and stem plants like cabomba and bacopa grow well. I dose all ferts to the water column - KNO3, K2SO4, and NaH2PO4.

TW


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## plantbrain (Jan 23, 2004)

Phil Edwards said:


> *RedDelPaPa*,
> 
> You're completely right that plants prefer ammonia/ammonium, but in nature as in our, aquariums ammonia/ammonium is very limited. It's quickly consumed by plants and microorganisms. Nitrate is by far the greatest source of nitrogen for plants. Even with artifical supplimentation (fertilization) with an ammonia based fertilizer the NH3/NH4 doesn't hang around long.
> 
> ...


Phil, it depends entirely on the concentration of NH4 and NO3 present.
Also, plant species to plant species(although much less so).

See page 107 of DW 's book, specifically the figure from Ozimek 1990.
I spoke to you about this at last year's AGA meeting.

If we have 0.5ppm to 2.0ppm of NH4, then for that plant, pants do prefer NH4, but how applicable is that?

It's not.

At less than 0.2ppm, the NH4 uptake is flat, no NH4 is being taken in by the plant, hardly a preferred form there.

When the NH4 is less than 0.5ppm or so, then NO3 starts being utilized and this rate is steady all the way down.

So in our case, NO3 is preferred, not NH4.

I've done more NH4 dosing than most anyone. I really do not find any difference in growth rates when the other variables are maintained.

Regards, 
Tom Barr


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## plantbrain (Jan 23, 2004)

RedDelPaPa said:


> Well, me and my Dad's 15 years experience says the least amount of biological filtration the better for planted tanks. I do know from our experience, an undergravel filter simply shuts down plant growth. I could take time lapse photos of our tanks and prove it. If someone can positively prove me wrong, please do so. For us, and for everyone else reading this thread.
> 
> Thanks,
> Red


I seemed to do very well with RFUG filters for a decade, I routinely took 20-30 bags of weeds to the local aquarium society auction every month as well as selling them to the LFS. Many folks from SFBAAPS and the SFAS saw the tanks.See APD post from many moons ago about all that.
I have about 200 species over that time frame so I know it works with all plants.

Bacteria makes a good back up in case the plants decline or lull due to a nutrient deficiency. If you add CO2 and have high light, you see this quickly, if not, you might think otherwise.

I can provide only NH4 via fish waste loading in non CO2 tanks, they simply do not have the growth rates needed to bottom out the nitrogen levels.
As you increase the growth rates, you rely more on NO3 inorganic dosing.

That's why folks cannot have more fish to supply all their Nitrogen needs for the CO2 enriched high light tanks.

Think about that for awhile.
Then try it and see for yourself.
You overload the system to fast.

Less light, no CO2 limits growth and thus demand for nitrogen.
Trace amounts of NH4 are enough.

Regards, 
Tom Barr


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## Phil Edwards (Jan 22, 2004)

plantbrain said:


> Phil, it depends entirely on the concentration of NH4 and NO3 present.
> Also, plant species to plant species(although much less so).
> 
> See page 107 of DW 's book, specifically the figure from Ozimek 1990.
> ...


Tom,

I prefer Porterhouse to Cube Steak, but when I don't have the money for a Porterhouse, I'll get the Cube. That doesn't mean I don't still prefer the Porterhouse.  I can see how NH4 might not get used in such small concentrations when NO3 is available in larger and more easily accessable quantities. I just wonder why you say it's not preferred? Wouldn't it be an issue of cost effectiveness or plain inability to obtain the NH4 in suitable amounts?

It seems to me to be an issue of availaibity rather than preference.


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## plantbrain (Jan 23, 2004)

Phil Edwards said:


> Tom,
> 
> I prefer Porterhouse to Cube Steak, but when I don't have the money for a Porterhouse, I'll get the Cube. That doesn't mean I don't still prefer the Porterhouse.  I can see how NH4 might not get used in such small concentrations when NO3 is available in larger and more easily accessable quantities. I just wonder why you say it's not preferred? Wouldn't it be an issue of cost effectiveness or plain inability to obtain the NH4 in suitable amounts?
> 
> It seems to me to be an issue of availaibity rather than preference.


Well, one could argue that. But..........in our tanks..........under the conditions we maintain and keep, as well as Redelpapa's or a non CO2 tank etc, plants pefer NO3 according ti the research.

Under flithy rich NH4, yes, many do prefer NH4, but certainly not all. 
In terms of ion efficency and energy at the cell level, NH4 is preferred.

But there are more NO3 inducible carriers and channels that allow more higher uptake when the NO3 concentration is high and the NH4 is low.

This applies to our situation.

If you want to discuss purly theoretical cases where we have 1-2ppm of NH4+ and NO3 under 2ppm, then I'd argue thatplants under those conditions prefer NH4.

It depends in other words.............I'm not making a blanket statement for every possible senario, I am saying in planted tanks that we keep, NO3 is preferred based on uptake.

By stopping filteration, you are introducing other things besides just NH4=> NO3 via bacteria.

Anyway, we know NH4 is removed much faster with plants, than bacteria and you can test that notion by removing the plants on a small test tank.

So the effect of NH4 loss by filtration is minimal as far as I can tell and I have tested this issue quite a bit.

The other issue is the difference in growth significant with our plants and does this outweigh the potential for algae should the plants falter for any reason.

Again, not likely.

Removing the bio material from a filter is the best way to see if the plant health improves...........but there is an issue with this.
Removing all that organic waste and media that impedes flow are like removing a lot of mulm and increasing flow rates.

That, rather than the NH4 vs NO3 is more probable of an issue.

Good/more current will help many tanks grow the plants better alone and less OM will help increase O2 levels for a time until the OM builds up again.

It's not a simple thing to consider ...........but folks want simple test and can figure a lot out without compicated test or expensive equipment.

It's their assumptions they have issues with and lead them astray.....Diana did and I did not even see the arguement till she presented it at the AGA and then it hit me. It depends on where on that gragh and under what conditions you are talking whether it supports NO3 or NH4 being preferred over the other.

In both cases, bacteria is still present on leaves, substrate etc and can convert NH4=> NO2/NO3.
Likewise substrate denitrrifyers can also remove some NO3.
But both issues can be addressed and tested(I have tried this) for........

Many assumed NO3 and PO4 were bad also without ever testing it even though the test itself is simple.

Be careful about the assumptions. They start myths and get folks into trouble when approaching aquatic horticulture.

Regards, 
Tom Barr


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## Phil Edwards (Jan 22, 2004)

Thanks for the clarification Tom.


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## plantbrain (Jan 23, 2004)

Well, I'm still learning meself

Regards, 
Tom Barr


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