Question About Plant Nutrients

Hubble Tea

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so I am reading the ecology of the planted aquarium and I'm not done but I don't think this question will be answered? I know that plant nutrients come from the soil and fish food/waste but when the nutrients in the soil run out is there any natural replenishing of the nutrients?
 

SeattleRoy

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HI Hubble Tea

Diana Walstad literally wrote the book on a 'natural aquarium'. I'm surprised if she didn't address your question but I will try to assist. The soil provides nutrients such as carbon, macro-nutrients and micro-nutrients when it is new. As the plants grow, and are trimmed we are removing some of those nutrients that were in the soil and absorbed by the plants for growth. Eventually one or two of the more critical nutrients become depleted and plant growth slows, stops, or plants become disfigured. Feeding the fish does result in nutrients being added to the tank from the urea and fish poop which replenishes the macro-nutrient nitrogen. Some foods also contain nutrients such as phosphorus. When a water changed is done if the local water has sufficient nutrients then the new water that is added to the tank may supply some of the micro-nutrients the plants need. Invariable however, a nutrient of two is no longer being replenished and the tank needs to be 'broken down' and re-done. Hope this helps!
 
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Hubble Tea

Hubble Tea

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SeattleRoy said:
HI Hubble Tea

Diana Walstad literally wrote the book on a 'natural aquarium'. I'm surprised if she didn't address your question but I will try to assist. The soil provides nutrients such as carbon, macro-nutrients and micro-nutrients when it is new. As the plants grow, and are trimmed we are removing some of those nutrients that were in the soil and absorbed by the plants for growth. Eventually one or two of the more critical nutrients become depleted and plant growth slows, stops, or plants become disfigured. Feeding the fish does result in nutrients being added to the tank from the urea and fish poop which replenishes the macro-nutrient nitrogen. Some foods also contain nutrients such as phosphorus. When a water changed is done if the local water has sufficient nutrients then the new water that is added to the tank may supply some of the micro-nutrients the plants need. Invariable however, a nutrient of two is no longer being replenished and the tank needs to be 'broken down' and re-done. Hope this helps!
Yes it does help! To clarify, When you trI'm plants you remove nutients but the water changes an fish food/waste brings them back, correct? Thank you!
 

bitseriously

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Hubble Tea said:
When you trI'm plants you remove nutients but the water changes an fish food/waste brings them back, correct?
It brings some/most of them back...

When I'm not fussing over my tanks (or outdoor plants in summer), I'm in the landscape trade. An early lesson in plant nutrition cited "Liebig's Law of the Minimum".
From Wikipedia: Liebig's law of the minimum The concept first stated by J. von Liebig in 1840, that the rate of growth of a plant, the size to which it grows, and its overall health depend on the amount of the scarcest of its essential nutrients that is available to it.

LLM can be represented thusly:
upload_2018-2-21_10-40-42.png

In these pics, the level of water in the barrel is analogous to plant growth or health (or in Leibig's case, crop yield). In the first pic, nitrogen is the least available nutrient. The level of N in the system (field, aquarium, etc.) is the driver (limiter) of plant growth. In the second pic, N has been added, and K (Potassium) is now limiting. After one adds K, it will be organic matter (again, recall that this is a terrestrial plant model), and so forth.
Going back to SeattleRoy info above, water changes and fish biology add all of the macros and most of the micro nutrients necessary for plant health (they raise the height of certain/most barrel staves). But some nutrients (staves) are not supplemented by WC or fish food/waste, which is where fertilization comes in (or teardown and start fresh if that's not possible/desirable).
 

SeattleRoy

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Hubble Tea said:
Yes it does help! To clarify, When you trI'm plants you remove nutients but the water changes an fish food/waste brings them back, correct? Thank you!
HI Hubble Tea

I think bitseriously covered it pretty well.

Regrettably it is unlikely that the water changes, fish food / waste will return what was lost from plant trimming in the quantities and proportions needed and invariably some nutrient will become limiting. Also, my experience that 'natural aquariums' work well with lower output light fixtures (PAR<45-50) and plants that can tolerate low to medium -low light levels which does limit the use of the more colorful aquatic plant species.
 
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Hubble Tea

Hubble Tea

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bitseriously said:
It brings some/most of them back...

When I'm not fussing over my tanks (or outdoor plants in summer), I'm in the landscape trade. An early lesson in plant nutrition cited "Liebig's Law of the Minimum".
From Wikipedia: Liebig's law of the minimum The concept first stated by J. von Liebig in 1840, that the rate of growth of a plant, the size to which it grows, and its overall health depend on the amount of the scarcest of its essential nutrients that is available to it.

LLM can be represented thusly:
upload_2018-2-21_10-40-42.png

In these pics, the level of water in the barrel is analogous to plant growth or health (or in Leibig's case, crop yield). In the first pic, nitrogen is the least available nutrient. The level of N in the system (field, aquarium, etc.) is the driver (limiter) of plant growth. In the second pic, N has been added, and K (Potassium) is now limiting. After one adds K, it will be organic matter (again, recall that this is a terrestrial plant model), and so forth.
Going back to SeattleRoy info above, water changes and fish biology add all of the macros and most of the micro nutrients necessary for plant health (they raise the height of certain/most barrel staves). But some nutrients (staves) are not supplemented by WC or fish food/waste, which is where fertilization comes in (or teardown and start fresh if that's not possible/desirable).
Wow, thanks! Well that sucks, ah oh well. Happy to know so I don't stress about it pointlessly though
 
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Hubble Tea

Hubble Tea

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SeattleRoy said:
HI Hubble Tea

I think bitseriously covered it pretty well.

Regrettably it is unlikely that the water changes, fish food / waste will return what was lost from plant trimming in the quantities and proportions needed and invariably some nutrient will become limiting. Also, my experience that 'natural aquariums' work well with lower output light fixtures (PAR<45-50) and plants that can tolerate low to medium -low light levels which does limit the use of the more colorful aquatic plant species.
what if I never trI'm my plants?
 

SeattleRoy

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HI Hubble Tea

I prefer not to have a tank that looks like a stagnant pond with weeds all over the surface and nothing underneath, but that is just my preference.
 

bitseriously

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I think a lot of folks new to aquarium (and house/landscape) plants think of them as static, as in they get to be a desired size and stay that way, but that’s far from reality - and from necessity.
For the most part, if a plants not growing, and growing well, it’s declining. Slow growth (at least among fast growing plants) is not satisfactory for our purposes. There are a range of satisfactory growth rates, that can be influenced by light and nutrient levels (both of which are under the control of the aquarist, along w co2 in many cases), but it’s that new growth that absorbs nitrates and other nutrients from the water, so removing them from the tank (as opposed to them simply being bound in plant tissues) only happens when you trim.
Conversely, if your plants - or parts of them - die back (wilt or melt) in the water, nutrients from the plants are returned into the water, which is the opposite of what we want (to say nothing of ammonia also being released through leaf decay).
It’s a conundrum, for sure. Whatever u end up doing, I suggest you start by aiming very low. Low light plants with fast growth rates. Easy-level plants. The best problem u could have is needing to trim.
 

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