Guaranteed stupid question

[7Enigma]

I know this is stupid, but I have to ask it.

Is there ANY plants that naturally prefer nitrAte over other forms of nitrogen (ammonia, nitrIte)? Chemically it seems easier to metabolize ammonia or nitrIte, but I'm hoping.

Reason I'm asking is I can see a common problem of tank crashing from the following:

1. fully stocked and cycled tank

2. Introduction of plants to the tank

3. Due to competetion of resources, less nitrogen is available for the bacteria

4. Bacterial population equilibrates to a lower level, nitrogen is kept in check due to the plant population

5. Plant dies due to me being an idiot/ not supplying fertilizer/ not supplying enough light/ supplying too much light and no CO2/ competition from outside source (i.e. algae, fungus, diatoms)

6. Tank cycles due to not enough nitrifying bacteria present

7. Fish die, I cry


Sound reasonable? Originally I had planned to start a tank (1st one in a long time) and for laziness and idiot reasons putting a plant or two in to keep nitrogen in check. Now I'm having second thoughts....

justin

 

[Jchillin]

fully stocked and cycled tank

That is the winning statement. If you have a full bio-load, your plants will definitely live.

No cause for concern...though I understand what you were getting at.

 

[malkore]

Well plants don't really use nitrite...just ammonia and nitrate as N sources.

You'll have plenty of nitrifying bacteria even with a fully planted tank and high light...to the point you could remove all the plants and the tank wouldn't cycle again. Nay, you wouldn't get ammonia readings either.

However your nitrates would start to skyrocket with nothing left to soak them up.

 

[7Enigma]

So then does any plants prefer nitrAte over ammonia? That's what I'm looking for. If plants don't really use nitrIte thats actually probably pretty great since from what i've read on this board and other sites the nitrIte to nitrAte bacteria grow more slowly than the ammonia to nitrIte, so a cycle would last a shorter time since you would in theory still have a large amount of the nitrIte converters even with plants (little to no competition).

I still then wondering about the ammonia converting bacteria. Say you have 100 units of ammonia present (and its replenished at a set rate), and you have no live plants. That 100 units will produce a set limit of beneficial bacteria (with slight fluctuations due to water conditions, temp, etc.). The system CANNOT support any more due to the limiting reagent being the food supply.

Now you introduce plants. Let's say they compete and take 10 units away (just generalizing as I have NO IDEA what amount they would use and I'm sure its temp/light/plant species specific). You now only have 90 units left to support the bacteria. The plants aren't putting nitrogen products into the water (i.e. generating more food), and if anything the light requirements have increased so you have more nitrogen sources removed from other factors (algae, etc.). So I guess it comes down to 2 things:

1. You have enough bacteria left that if the plants are suddenly removed, the ammonia to nitrIte converting bacteria can bounce back to absorb the newly available ammonia. And since the plants apparently don't use nitrIte, the slower growing nitrIte to nitrAte converting bacteria's numbers are relatively unchanged from a tank with no plants.

2. You had enough plants that the amount of ammonia to nitrIte converting bacteria can not replicate fast enough to absorb the extra ammonia, and you have problems.

I'm sure its a combination of the 2, but I'm still interested in my original question, since a plant that primarily uses waste products from bacteria (nitrAte) would not cause this possible problem.

justin

 

[Simpte]

No. No aquarium plant perfers NO3 over NH4 or NH3. NH4(NH3) is easier to use than NO3. Unfortunately NH4 is peferred by algae also which cannot readily utilize NO3 like plants can. This is why we dose No3. The NH4 statement can be test by adding urea to a fishtank. Watch the greenwater bloom before your very eyes. In the grand scheme of things, bacteria ALWAYS get first dibs over plants and algae when dealing with NH4 and NO2. The problems occur when there is too much ammonia for the bacteria to convert readily. Thats when algae gets it. In short the nutrient consumption works like this..........

NH4/NH3 -------------> bacteria gets first. Leftovers goes to algae (microphytes) and if any is then left plants (macrophytes)

NO2 -------------> bacteria win again and then algae then plants

NO3 ---------------> Plants then algae. Plants can use more energy to convert it into a readily available form.

Keep in mind that algae and bacteria can use amounts of NH3/NH4 that we cannot readily test for.

"Algae have no problem taking up less than 20ppb of NH4 depending on the species in question, they will also use organic N as well as NO3.

You will kill your plants long long before you will hurt/limit algae.

If the total N is less than 20 ppb, that is extremely rare and rather tough to measure also.

Organic N can supply a fair amount of N to the algae also, Organic N is decomposed into NH4 at a slow rate. Harder to measure if you only sample from the water column as it is typically used up as it is produced.

Regards,
Tom Barr"

 

[7Enigma]

Simpte,

Thank you so much, you answered my questions perfectly and it was very understandable. So from your post and my research, I think I'll start with a plantless (live) tank first for at least several months before even thinking about getting a plant or two. Then maybe experiment with a java fern or other low light requiring plant and see how that lives. If it appears to be doing well, I might add another. Thanks!

I might also get a very small tank (1-5gallon) and use it for a biological filter tank, that is, if I see the main tank going downhill for whatever reason (due to N levels or other competators), I'll quickly try to seed the small tank and dose with ammonium chloride to bolster the main tank. Sounds like a low maintainance safe way to always be sure I could have a large supply of bacteria...

justin

 

[czcz]

If you address 5 on your original post, the competition between plants and bacteria is not so important in terms of a successful aquarium. I use plants as biofilters in all but one aquarium (goldfish) and my fish are good. This is one of the main parts of the Diana Walstad method: http://www.aquabotanic.com/plants_and_biological_filtration.htm Just throwing it out there. Do not be afraid to add a couple of light appropiate plants to your plans: they will not hurt anything.

 

[Jchillin]

Indeed...obviously there is somewhat of misunderstanding here. I added plants almost immediately after I set up my 75 gal tank. I used traditional low-light plants and increased both my bio-load and my plants until I got where I am now.

I originally found my nitrates in the 20's on a regular basis...tank cycled almost on it's own as I never really experienced the typical ammonia or nitrite spikes.

You can definitely add low-light plants. Neither the plants or bacteria will suffer.

 

[7Enigma]

I don't think there's a misunderstanding here, maybe just being overly cautious (ie sudden catastrophic death of plants during a sudden CO2 loss or power outage). I'm bad at explaining but let me try a different way.

As far as I know nitrifying bacteria do not use CO2. They also don't use trace elements like plants do (or at least to the same degree). They also don't require light the way plants do. This is 3 more resources IN ADDITION to the nitrogen requirement. Because of that, if any one of those is reduced away from optimal levels, the amount of nitrogen that can be taken up is reduced. No CO2 available, no respiration=plant dies=possibly ammonia spike in tank. Same thing for sunlight, and probably trace elements (though these normally don't get fully depleted due to PWC's).

Now there are googles (little extreme? ) of bacteria present in a well cycled tank. There are normally a small number of plants in the tank. Kill 1 plant, and the % nitrogen reduction ability lost is much greater than killing a couple of bacteria.

So then we come to the $60,000 question. Are nitrifying bacteria more/less hardy than plants. I think this is where its tough to answer. You lose any of those 3 above resources and the bacteria laughs and keeps on chugging, the plants stop working or work less efficiently. But what if a foreign agent comes into play (lets say an antimicrobial). This will most certaintly wipe out the majority of the bacteria present in the tank (and maybe your fish, but lets pretend the fish are fine/immune), but the plant might be able to overcome this and continue pumping away.

So from this last question it MAY be beneficial to have some plants present, as you have a buffer during the, "oh heck, someone dropped the Dial soap in the tank!", whereas with just bacteria in the tank you might have a total loss.

I'm gonna have to mull this one over a bit...

 

[czcz]

Grain of salt as I am an intermediate aquarist at best.

This is 3 more resources IN ADDITION to the nitrogen requirement. No CO2 available, no respiration=plant dies=possibly ammonia spike in tank. Same thing for sunlight, and probably trace elements (though these normally don't get fully depleted due to PWC's).

This is not true of most plants in the hobby. Supplemental CO2 injection is generally used by those seeking algae-free medium light or higher tanks. If there are nutrients without appopriate plant growth and density, opportunistic algae would probably compete with bacteria for it.

Kill 1 plant, and the % nitrogen reduction ability lost is much greater than killing a couple of bacteria.

If plant density is high and growing, the other plants will more than make up for it. I have dying emersed stems in a couple of tanks (no biomedia) without detectable ammonia or related algae, for example.

As you can see in the Walstad study, plants like Anacharis uptake ammonia/ammonium very quickly. True that it is aguable that it is outcompeting bacteria, but it is also hard to kill. As long as you keep them growing, plants are only healthy for your tank. Also do not forget that as soon as you remove plant mass with trimming, you are removing tons of nutrients from the system. Bacteria does not do this. You can also see this applied in Goldie and Mbuna aquariums with high bioload and planted filters/sumps. Hopefully jsoong reads this thread and posts.

In the end bacterial colonies appear to be very adaptable once established. You can see this by cycling with 3ppm ammonia, building the colony, and timing drop of a 4ppm dose.

Another avenue to explore may be algae filters/ATS, which many argue and measure to be better than any biological filter in terms of fast uptake, adaptability, and nutrient export. ashdavid has applied this in an 1850gal tank and has advised members here. (He also talks about his 400gal filterless high-light tank here.)

I think this thread is far from stupid, for what its worth. I think the most logical solution is to take the steps necessary to keep undemanding plants growing, while using an excess of biomedia for your bacterial colony for saftey, but I am of the opinion that any planted tank is superior to an unplanted one. I hope this helps some.

 

[7Enigma]

czcz,

Great post as well. The one thing I didn't mention was the amount of bacteria present on the leaves and roots of the plants themselves. This sort of makes them a pseudofilter in that even if the plant were to die the bacteria on the plant could effectively remove a good portion of contaminants. I havn't dealt with decomposing plant waste, but would imagine it wouldn't be horrible right when the plant dies, so there is a buffering period where you could leave the plant in the tank (even though dead), while the bacteria on the leaves/stem/roots could continue to convert ammonia and nitrate.

And I read through that study and found it very interesting. Of notable interest was the 4 plants mentioned that preferred nitrAte over ammonia. I did not take the time to look them up to see if they are viable aquatic plants (and for my personal tank they would also have to be low light), as they would be the perfect plant for almost all tanks (especially those people that don't do PWC's often or ever).

justin