[johnnymax]

Do the plants remove the ammonia directly, or does it have to be converted to nitrite then nitrate for the plant to use it? I am wanting to have a large tilapia tank with water circulated through a large planted tank to scrub the water. Think a system like this can be set up to work?

I am going to try something, just not sure what...

 

[jefft72]

Your cycled tank will break down ammonia to nitrite to nitrate. The N-bacteria are all responsible for this. I believe that plants will take up some nitrate and with enough plant mass perhaps keep levels down. Water changes are recommended and your own system needs could change based on the bio mass.

Tilapia are great looking fish, but I would imagine that having such a large species would require quite a bit of mechanical filtration coupled with regular water changes.

 

[johnnymax]

I am afraid you are right and the minimum amount I can buy is 5 lbs. of live fish. That's a lot of fish! I may put some in the tanks and some in the oven, LOL They are about 3 to 5 fish per lb, so they are BIG already. I convinced a Tilapia hatchery to sell me some out of season.

 

[timwag2001]

plants prefer ammonia to nitrate

 

[MarkMc]

plants prefer ammonia to nitrate

If memory serves me correctly they prefer ammonium which is only present at a pH under 7. I can't recall where I read that so it may not even be a proven fact. A lot of things I read years ago concerning this hobby are now debunked such as phosphate causing algae. Anybody want to buy some X-Phosphate? lol

 

[timwag2001]

i'm not sure about whether they prefer ammonia at a certain ph. i think that ammonia isnt as toxic for fish if it's at a certain ph though. i'm not positive on either.

 

[Darkblade48]

I believe ammonia, under its pI (isoelectric point) will be positively charged as the ammonium cation, is less toxic to fish.

Then, we can get into another discussion about how Nessler test kits detect total ammonia whereas salicylate test kits only test free ammonia.

 

[PRSRocker3390]

If I'm wrong, someone correct me but ammonia turns to ammonium (NH4+) when the ph is below 7. Above 7 and it is present as ammonia (NH3). Also a lot of those products like ammo-lock or any ammonia ridding products do this as well. Some inexperienced hobbyists think the ammonia goes away with these products but your test kit will probably still show ammonia is present and levels will still be elevated. That is because these ammonia fixing chemicals just convert toxic ammonia to a much less toxic form, ammonium. Ammonium is just an ionized ammonia.

 

[MarkMc]

Ammonia is often cited as a cause of algae. Are there any studies that show plants prefer ammonium to nitrate?

 

[EdTheEdge]

I don't have the time to get into the science of the hobby.... And my opinions might not help the OP.... But to answer the basic question..... Plants are filters. IMO they will improve overall water quality (to a certain extent). They are after all "filter feeders". That said you still need to provide them with the proper parameters for them to do their "job" wether it is ammonia, ammonium or nitrate...

Somewhere I have read that plants prefer ammonia to nitrate but will use nitrate just as readily as ammonia. It just takes one extra metobolical step. Which leads me to believe that ammonia will be taken up first and nitrate second.

Of course I could be totally wrong on this....

 

[Darkblade48]

Also a lot of those products like ammo-lock or any ammonia ridding products do this as well. Some inexperienced hobbyists think the ammonia goes away with these products but your test kit will probably still show ammonia is present and levels will still be elevated.

The test kits will only show the presence of (total) ammonia if it is a Nessler based test kit. Most "ammonia" test kits that I see nowadays are salicylate based, meaning they will only indicate levels of free ammonia and will not be able to detect ammonium.

 

[PRSRocker3390]

Yes, you are right. I have many people come to my job saying they used ammolock and still have an ammonia reading. But these are not readings of ammonia because some of the kits we sell detect ammonium as ammonia. I mean in theory it is ammonia, just a positive charged ion of it. It's just also not as toxic as straight NH3. I am pretty sure the API kits still measure ammonium as a ammonia unless they have changed. I remember using one at work that detected ammonium.

IDK, it's just what i've observed and learned over the years but I don't know how accurate I am.

 

[fish h20]

You need to look into an algae scrubber. If you are just looking to filter the water this would work alot better than plants. They are easy to make and algae is easier to grow anyway.

 

[Church]

I've posted this info in another thread before, but it seems appropriate here:

Aquatic plants do take in ammonium for N. In some cases, plants will actually STOP taking in nitrates when ammonium is present in certain quantities. This seems to suggest that they actually prefer ammonium over nitrates. Here's a quote from an article over at Aquabotanic (bold emphasis mine):

Plants, algae, and all photosynthesizing organisms use the nitrogen from ammonia- not nitrates- to produce their proteins. If the plant takes up nitrate, it must first be converted to ammonium in an energy-requiring process called ‘nitrate reduction’.

Nitrate reduction in plants appears to be the mirror image of the bacterial process of nitrification. Nitrifying bacteria gain the energy they need for their life processes solely from oxidizing ammonium to nitrates; the total energy gain from the two-steps of nitrification is 84 Kcal/mol. The overall reaction for nitrification is:



NH4+ + 2 O2 >> NO3- + H2O + 2 H+



Plants theoretically must expend essentially the same amount of energy (83 Kcal/mol) to convert nitrates back to ammonium in the two-step process of nitrate reduction The overall reaction for nitrate reduction is:



NO3- + H2O + 2 H+ >> NH4+ + 2 O2



The energy required for nitrate reduction is equivalent to 23.4% of the energy obtained from glucose combustion [5]. Thus, if nitrifying bacteria in biological filters convert all available ammonium to nitrates, plants will be forced-- at an energy cost-- to convert all the nitrates back to ammonium. This may explain why several aquatic plants (e.g., water hyacinth, Salivinia molesta, hornwort, and Elodea nuttallii) seem to grow better with ammonium or an ammonium/nitrate mixture than when they are forced to grow with pure nitrates [10]. The nitrogen cycle is often presented incorrectly to hobbyists as nitrifying bacteria converting ammonium to nitrates and then plants taking up nitrates. Actually, it consists of both plants and bacteria competing for ammonium. Only if plants are forced to, will they take up nitrates. Thus, nitrates may accumulate even in planted ponds and aquariums.

Taken from http://www.aquabotanic.com/plants_and_biological_filtration.htm.

 

[mistergreen]

yes, plants and algae will take up ammonia. Are you planning to culture tilapia for food?

for optimum scrubbing, it's best to use marsh/marginal plants and floating aquatic plants. They can take up CO2 directly from the air and you don't have to worry about injecting CO2.

 

[kid creole]

I have seen plant scrubbers in practice many times around the internet, never in person. Most of them used the plants in a hydroponic/emersed condition.

 

[plantbrain]

Here's some good info on algae:

http://www.sciencedirect.com/scienc...serid=10&md5=1923dc1d2f5fd2d1f32f0f49ffc4f2f9

Like plants, they will use both if you offer them both at the same time.


Here's a good paper on NO3 from roots and shoots and tells why maintaining good NO3 levels is critical to stable growth, uptake of N, something that NH4 often in the water column is unable to do very well.

http://www.sciencedirect.com/scienc...serid=10&md5=934e9d5886d260027c07cce06c3880a5

http://www.sciencedirect.com/scienc...serid=10&md5=32624a18eb452d8f60e656969db1baa2

Read the 2nd to last line, which applies to aquariums.
Plants will use both and are opportuntistic, same applied to sediment vs water column, NH4 vs NO3.



A wiser approach, at least management wise, and that reduces dosing issues:

1. Use NH4 in sediments, where they are able to be bound and locked in clays for long term NH4 sources, and from fish waste. NO3 cannot be bound up in the clays, and this is why it is lost and often ends up in rivers, ground water etc, no binding. NH4 does......

2. Use stable good NO3 dosing to the water column. If you use a test kit, then use a known standard to ensure the reading for NO3 is actually correct and do not just pray and guess that the test kit is correct(often it is not).

Unlike "either.... or" thinking........this way you cover both your bases for the type of N supplied for plants. You also cover both locations for this and the other nutrients for plant leaves and roots.
So this approach allows the plants to pick and chose what they want for each of the 300-400 or so species we keep these days.

Still, nutrients are pretty easy and simple and have little effect if the light and CO2/current are not well balanced. You cannot make any conclusions without first addressing light and CO2roud:

Many seem willing to go on about things, look things up, be all critical over N or P....... and over look light and CO2. Folks get lost in the details and often do not look at the bigger larger picture.

Careful not to do that.

Regards,
Tom Barr

 

[plantbrain]

This paper was cited by a book from Diana Walstad.

http://depot.knaw.nl/3369/1/21259.pdf

The paper is cited here in its entirety for a reason(a full discussion).
It should be noted, this is for only 2 species of pklants that are very fast growing weedy species.

The results may not apply too all plants.

If we look at the various treatments in this paper, we can see that 2ppm of N-NH4 is really high, they also have a 5ppm treatment for both N-NH4 and N-NO3 where the growth rates are reduced compared to 2ppm.

NH4 is preferred if both nutrients are at the SAME concentrations.

Try adding 10-20ppm of NH4 sometime to an aquarium:icon_idea
We can and do do this for NO3 however. 19C is fairly cool water, and we can also see no CO2 enrichment is being used and that the light was pretty low.

Since we have fish, this issue no longer is a fair comparison. We cannot make the NH4 NO3 issue equal for aquarium management.
We can however, add plenty of NH4 to sediments without impacting the water column and the fish etc.

This study did not add some other nutrients for growth also.
We typically do and have some source coming in no matter what type method used for the aquariums(sediments, dosing, fish waste etc). A small 1 liter tank with only lake water and a fast growing weed will likely be limited by something other than these 3 measured parameters.

Also, adding CO2 will enhance growth rates by a factor of 10-20X, but only perhaps 3-4x at this low light level. So that will influence the results dramatically.

While interesting, from the aquarist perspective, management and what is best for plants is typically the question. Do we need higher growth rates?

Many cases, the answer is a resounding NO!

Light is a better choice to changing the rates of growth to suit, it's much more stable, non toxic, easier to test, CO2 will also enhance growth far more than the choice between these two forms of N also.

Read the paper, but also realize that there's no traces being added(at least none in the methods is mentioned), and that CO2 enrichment and the many other species will/may respond differently.

And look at the management goal for yourself, you might not want more growth, particularly if you have figured out a good balance for light(generally less than you thought) and are using CO2 well.

This(NH4 vs NO3) is hardly any silver bullet.
Add more fish if you wanna dose NH4. Slow metered dosing of NH4, add it to the sediment etc.


Regards,
Tom Barr

 

[seds]

Add more fish if you wanna dose NH4. Slow metered dosing of NH4, add it to the sediment etc.


Regards,
Tom Barr

QUOTE for TRUTH

That was an interesting read. I learned a lot.

 

[Robert H]

Has anyone really been far as decided to use ever go want to do look more like?

ahhh... what? :drool:

That quote Church posted was from an article Diana Walstad wrote for my web site. Tom and Diana are the experts on this. There is nothing I could add, other than the fact all of the nitrogen products we use are some form of nitrate or urea, right? I do not know of any ammonium product. You do not want to add straight ammonia to your aquarium