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Discussion Starter · #1 ·
So this question is of course related to my poop question. In a well planted tank will plants absorb ammonia faster than bacteria can convert it to nitrite/nitrate ? Is there an easy way to measure how much ammonia plants are directly absorbing? I suppose low-tech vs high-tech might matter here - still I wonder if plants can influence tank water stability to the same degree as bacteria cycle ?
 

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The only way to test this would be to put some plants in Ammonia water without a filter. I love all the possible experiments you raise in your threads. I had a thread on this same question that went unanswered. The answer I came up with on my own through experience is, "No, plants do not process Ammonia faster than bacteria." The plants barely helped me at all in my uncycled tank. Water changing was my only relief.
 
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Hello. Both urea and ammonia are good fertilizers that are already being sold by a manufacturer. They are present, in variable quantity, in aquariums. And that quantity has to be = 0, if the aquarium is well cycled. The brutal work of the nitrifying, aerobic and anaerobic bacteria, allows only a minimum of these waste substances. Note that if the PH becomes alkaline (> 7) the ammonium becomes ammonia, this being very poisonous to fish and other inhabitants.
Therefore I think that in a stabilized (planted) aquarium there can be little ammonia and that little amount can be used by the plants. Another different thing is that you fertilize with that type of fertilizer, which then will reach your hungry plants immediately. That's my opinion.

The only way to test this would be to put some plants in Ammonia water without a filter. I love all the possible experiments you raise in your threads. I had a thread on this same question that went unanswered. The answer I came up with on my own through experience is, "No, plants do not process Ammonia faster than bacteria." The plants barely helped me at all in my uncycled tank. Water changing was my only relief.
Ok.
 

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Industrial waste water filters can process ammonia at a rate somewhere near 60mg/L/h. That's several folds higher than what plants can do. Hobbist filters won't be that optimized, but the potential still holds. There shouldn't be any worry of competition.
 

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My understanding, from the aquaponics and hydroponics world, is that plants will take up all of the NH3/NH4 that they need, before BB can limit that uptake. It seems that the quantity of BB that develop are what is limited, in terms of what is left over after the plants take what they want. However, a filter that houses BB in high concentration may disrupt this process by force-feeding the ammonia into this ammonia vacuum cleaner.

Here is a current article that describes this in the best detail that I have seen: Comammox Nitrospira

This study also confirmed that most of the BB are Nitrospira (which we knew) and, which, we thought to convert the NH3/NH4 into Nitrite. The interesting part of this new study is that most of the Nitrospira that convert the ammonia were found to actually be what are called Comammox Nitrospira. These Comammox Nitrospira convert the ammonia directly into Nitrate.
 
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This is a very interesting field because plants cannot move and have to control what is around them through membranes which regulate the uptake and transport of nutrients.

Plants also don't classify nitrate or ammonia and actually have a range of proteins to handle each type.

Whether these proteins work to accept more NO or NH are affected by a bunch of things such as the ratio of NO vs NH available, acidity, developmental stage of the plant, presence of other nutrients such as K etc. Plants also develop proteins to take advantage whats out there.

Also plants have to assimilate the nutrient and distribute it to its shoots and leaves.

The general research is that NH takes up less energy but needs a bit of NO to work.

The best discussion I have on this is performed on terrestrial plants and can be found here: Interactions between nitrate and ammonium in their uptake, allocation, assimilation, and signaling in plants

But Deanna is right that this understanding is a bit pointless because controlling NO and NH levels are extremely difficult due to filtration and most of us actually end up living with NO. The ease at which NH is assimilated by bacteria vs NO reveals quite a bit, if you think about it.



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Whether these proteins work to accept more NO or NH are affected by a bunch of things such as the ratio of NO vs NH available, acidity, developmental stage of the plant, presence of other nutrients such as K etc. Plants also develop proteins to take advantage whats out there.
This comment about NO3 and NH3/NH4 interactions is an important point and you also nicely condense, for further investigation for those interested, Mulder chart-type interactions and optimal pH levels for nutrient uptake.

You might find this well-regarded oldie useful: Nitrogen Cycling in Planted Aquariums

Although it can be tricky to compare processes of aquatic plants to terrestrial plants, providing both NH3/NH4 and NO3 is necessary for optimal growth in both. Much, sometimes all, of the optimal TAN is already provided by our animals. Dosing NO3 is far more forgiving than dosing ammonia, particularly when using ammonium salts. Urea is safer, as N is less available to algae in that form.

The way I view it is to add enough TAN, for plants, without causing a noticeable algae outbreak. This ‘breakeven’ point, I suppose to be the maximum uptake point of a given plant mass. Then, to make sure that the plants aren’t N limited, the NO3 levels are easily maintained in a wide range of ppm. I don't use bio-media in my filter for this reason. For novices or those not inclined to go too deep into this, don't bother trying to dose TAN. Your animals will go a long way to getting you there. Just be sure that your NO3 isn't too low.
 

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So this question is of course related to my poop question. In a well planted tank will plants absorb ammonia faster than bacteria can convert it to nitrite/nitrate ? Is there an easy way to measure how much ammonia plants are directly absorbing? I suppose low-tech vs high-tech might matter here - still I wonder if plants can influence tank water stability to the same degree as bacteria cycle ?
That's an interesting question and one I've tried figuring out how to test to my level of satisfaction for years. Isolating a cutting of a plant in a sterile nutrient bath is about the only way to accomplish this but the hardware requirements are out of my league. In the end, it doesn't really matter though, since our aquariums are dynamic ecosystems and we can't, for all practical purposes, isolate the plants from the other biogeochemical processes going on in the tank.

One thing I've really wondered about is how well urea or ammonia/ammonium supplementation would work when using a reverse under gravel filter to constantly bathe the roots and substrate microbes in fresh water. I used one of these in a tank decades ago now and loved it, but the only source of N I added was NO3.

While NH2, NH3, and NH4 are certainly energetically favorable forms of N for plants and they do take up what they can get their greedy little roots on as fast as they can, once the biological system is established any NHx gets processed so quickly that we're left with NO3 as the main persistent source of inorganic N in the tank. I've tried various raw chemicals with an NHx component in them in the past, with acceptable results. I just didn't find the small difference to be worth the potential hazard of an accidental overdose and NHx spike.

All that being said, if you find value in using something with NHx, you do you. :)
 

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One thing I've really wondered about is how well urea or ammonia/ammonium supplementation would work when using a reverse under gravel filter to constantly bathe the roots and substrate microbes in fresh water. I used one of these in a tank decades ago now and loved it, but the only source of N I added was NO3.
Same here. I used an UGF for decades and stopped using it when I went high-tech about 6-7 years ago. I believe that they do deliver that ideal mix of elements to the roots, but not the roots that are in the substrate, so much. My stems would develop extensive root systems that would exist below the UGF (in the open water under the substrate), unlike the smaller root systems that develop in my substrate, now. My Java Fern roots almost covered the entire bottom of my 29-gal in this water-only area. It was quite a mess of nice white roots under there (I could see it through the bottom of my tank). I do believe, though, that the substrate creates that right mix of elements that were then gently moved directly into that root zone-only area.

Of course, now, UGFs are deemed unsatisfactory ...but I sometimes wonder.
 
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Same here. I used an UGF for decades and stopped using it when I went high-tech about 6-7 years ago. I believe that they do deliver that ideal mix of elements to the roots, but not the roots that are in the substrate, so much. My stems would develop extensive root systems that would exist below the UGF (in the open water under the substrate), unlike the smaller root systems that develop in my substrate, now. My Java Fern roots almost covered the entire bottom of my 29-gal in this water-only area. It was quite a mess of nice white roots under there (I could see it through the bottom of my tank). I do believe, though, that the substrate creates that right mix of elements that were then gently moved directly into that root zone-only area.

Of course, now, UGFs are deemed unsatisfactory ...but I sometimes wonder.
Perhaps "unsatisfactory" from an actual filtration standpoint, but it's hard to argue with a well-oxygenated root zone getting regular input of nutrients under the right circumstances. I'm seriously considering using an RUGF again in the future once the Mrs and I get settled into a new house and have space to set up a decent sized tank for her.
 

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Perhaps "unsatisfactory" from an actual filtration standpoint, but it's hard to argue with a well-oxygenated root zone getting regular input of nutrients under the right circumstances. I'm seriously considering using an RUGF again in the future once the Mrs and I get settled into a new house and have space to set up a decent sized tank for her.
I'm not concerned about N cycling in a UGF, but don't want to disrupt my entire tank with a tear-down (which would include removing the sand component) ...unless there is evidence (even anecdotal, from the right person) that a noticeable enhancement occurs. I'd be concerned about too much flow, so I would probably use airstones rather than the powerhead approach that I used to do. Why would you do a RUGF? I would think that, with very low flow, the opposite would be better, particularly when the main objective is to not use it as a bio-filter.

If you do decide to do it, I would be very appreciative if you would report on it.
 

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My goal would be to use the RUGF more as a way to circulate water in and through the root zone on a low/modest light tank with species that root heavily. The Mrs wants to do a fancy goldfish tank eventually so I can see this as a good way to help maintain a cleaner substrate while maximizing uptake of the N and P those piggies like to produce. The idea of running a UGF with a normal circulation pattern has some appeal too; especially if I can rig up canister filter intakes to the plates. Who knows if I'll ever actually do it, but it's fun to think about and I'm too curious for my own, or my tanks', good. :)


If a 20 year old anecdote works for you; I did a (for the time) high tech 20 high crypt tank with an RUGF under a couple inches of Flourite and was very happy with the results. show49.html. Please remember this was back in 2002 and the information available for biotope aquariums was rather limited then.
 

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Yes, I can recall thinking "Why would I want to do that?!" whenever someone suggested using CO2 to me, back then. I was always happy with the low-tech plants in my low-tech setups using the UGF, but it's pretty hard to not do well with undemanding plants and medium light.
 

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Discussion Starter · #14 ·
There are two ways to take this question - one is effectiveness of plants at biological filtering but conversely if having a large fish load improves plant growth due to plants ability to absorb more direct ammonia. If we consider the later one could argue the question was ill phrased as one could ask at what point do the plants have the opportunity to absorb ammonia directly. In one of my tanks i have what could be deemed as an extremely slow moving reverse ugf - it is in fact the low tech tank where the plants do fairly well. I'm not willing to directly attribute it to the ugf plates because the sister tank (also a low tech tank) never produced such growth despite having the same design. Since the sister tank leaked after a year (aqueon tank quality is quite top notch); i removed the plates when replacing the tank.
 

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Yes, I can recall thinking "Why would I want to do that?!" whenever someone suggested using CO2 to me, back then. I was always happy with the low-tech plants in my low-tech setups using the UGF, but it's pretty hard to not do well with undemanding plants and medium light.
Truth has been spoken! Two of my favorite tanks were low-tech and/or no-maintenance other than topoffs. They were both heavily planted and modestly stocked. The 55 was fairly low light as we'd consider it these days, but the 90 was quite high light for the time and grew a decent amount of algae. I had enough going on with grad school that I didn't care about maintenance and just let the plants do their thing. The algae ended up being a benefit as I had a lot of samples to play with when taking a class on algae. The prof thought that was pretty cool!


There are two ways to take this question - one is effectiveness of plants at biological filtering but conversely if having a large fish load improves plant growth due to plants ability to absorb more direct ammonia. If we consider the later one could argue the question was ill phrased as one could ask at what point do the plants have the opportunity to absorb ammonia directly. In one of my tanks i have what could be deemed as an extremely slow moving reverse ugf - it is in fact the low tech tank where the plants do fairly well. I'm not willing to directly attribute it to the ugf plates because the sister tank (also a low tech tank) never produced such growth despite having the same design. Since the sister tank leaked after a year (aqueon tank quality is quite top notch); i removed the plates when replacing the tank.
I'd say plants are a significant source of inorganic nutrient filtration, but aren't nearly as good at processing dissolved organics as bacteria. If you end up with a robust microbial community that chews through particulate and dissolved organics to the point where inorganic nutrients are released then you've got one heck of a good ecosystem going. That's one reason I think UGFs can be useful; the oxygenated water going through the substrate provides one hell of a good environment for bacteria that process physical organic matter which only benefits the plants and improves nutrient availability. Flow rate doesn't need to be fast; it just has to be fast enough that anaerobic zones don't form.

As for the opportunity for plants to directly take up ammonia; it's happening at all times. My supposition is it really depends on intake rates into the filter and/or the amount of biofiltration in the filter. The greater the contact time between the plants and ammonia-laden water, the greater the opportunity they have to take it up.

This is an interesting discussion and is giving me some food for thought. Thank you both!
 

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Discussion Starter · #16 ·
Yea - in my 120 i finally shut off co2 after 18 months simple because the weekly management was a problem. I've attached a picture - most of the plants are the type you can't really easily prune being swords and java fern as well as some large anubia but everything is super sized. The other two pictures show my 40B when it was set up in may and again in april. It is so overgrown you can't see any of the driftwood but it is still in the tank... We can argue which look is nicer but certainly co2 does cause its fair share of problems. Conversely the 40B has a few plants that really do benefit from co2 and are very hard to grow without - they are hard to see in the picture because they have an inverse problem and have to deal with shading from from plants that grow too well with co2.
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The last picture is my 29 a low tech tank (the one without the ugf plates). This was discussed in another thread which you commented on - i disagree that the problem was light intensity but rather an issue with 'bad' gass from the substrate for which i ended up replacing the substrate and that seemed to have resolve the most serious issues:

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Yes, I can recall thinking "Why would I want to do that?!" whenever someone suggested using CO2 to me, back then. I was always happy with the low-tech plants in my low-tech setups using the UGF, but it's pretty hard to not do well with undemanding plants and medium light.
 

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It's hard to see in the pictures; are you still running UGFs on the first tanks? I see a number of air-driven sponge filters but can't make out UGF updraft tubes.

Something else to ponder- in non-CO2 tanks, air stones can help get a surprising amount of CO2 into the water. I used a couple hundred 5 gallon buckets with only an air stone for circulation and gas exchange, under 30% shade cloth, in the North Texas summer for my plant growing experiment and we got decent growth out of the three species. I wouldn't be surprised if all those air-driven filters are helping dissolve enough CO2 for your plants to grow, if not nearly as much as CO2 injection, given the tech level of the tanks.
 

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Discussion Starter · #18 ·
I do not run the ugf in these three tanks. The tank that runs a ugf is a slight mess right now because a couple of months ago i had to use furan-2 and it killed off a lot of the plant life. It is recovery well i just don't have a recent picture. Also the ugf is not hooked up to a air pump - the plates are there and they run up against a hamburg matten filter so the water flow from that filter draws a small amount of water from the area under the ugf (in theory) with the bulk from the area above the ugf. I have sponge filters in all my tanks - the fishes love them for bio film so it is an added plus if they increase the co2.

Here is a picture of the 29 with the ugf. One thing i have learned is that fish poop != nitrate as this tank nitrate levels stays around 20.

This tank is also able to grow some more difficult plants like purple aflame (there is one in the back you can't see in the image - it is small but puts out new leaves at a steady rate):

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