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post #1 of 26 (permalink) Old 09-15-2014, 11:45 PM Thread Starter
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Question Kh2po4

What happens to plants in high lighted tank if you stop dosing KH2PO4?

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post #2 of 26 (permalink) Old 09-15-2014, 11:53 PM
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If you eliminate a nutrient growth will stop and algae will take over.


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post #3 of 26 (permalink) Old 09-16-2014, 12:01 AM Thread Starter
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Quote:
Originally Posted by greaser84 View Post
If you eliminate a nutrient growth will stop and algae will take over.
I agree not.


anyone else?

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post #4 of 26 (permalink) Old 09-16-2014, 12:15 AM
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Are we talking dosing is the one and only source of KH2PO4?


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post #5 of 26 (permalink) Old 09-16-2014, 12:18 AM
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If you stop dosing an essential nutrient like P or K, the plant will stunt and algae will take over.
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post #6 of 26 (permalink) Old 09-16-2014, 03:03 AM
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Originally Posted by Solcielo lawrencia View Post
If you stop dosing an essential nutrient like P or K, the plant will stunt and algae will take over.
Correct!

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post #7 of 26 (permalink) Old 09-16-2014, 03:15 AM
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According to deficiencyfinder, the plants will scavenge their oldest leaves for phosphorus. New growth will appear normal, but old leaves will quickly die.


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post #8 of 26 (permalink) Old 09-16-2014, 03:51 AM
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If that was the only source of P and there was no reserve then there would be problems. As noted by our numbered member plants can use a certain amount of the phosphorus that is in their old leaves, recycling it into new growth, but it does not last long. They cannot scavenge every atom of phosphorus.

However, P is in reasonable supply in fish food, so your plants might be just fine if you are feeding fish or shrimp in the tank.
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post #9 of 26 (permalink) Old 09-16-2014, 07:46 AM
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Smile Not Sure of the Honesty

While it is true some plants scavenge themselves for nutrients and we could go through a whole list of alternate sources of every nutrient, and assuming JoraaN is an honest person asking an honest question.

The result in a closed aquatic environment of the sudden removal of two major nutrients is going to be severe limitation of growth.



Even though a particular plant may have the ability to sustain itself by relocating nutrients and allowing holes to form (thereby conserving Potassium).



There is still going to be an increase in the wastes, probably seen as an increase in total organic carbon, an increase in total Ammonia, assuming a healthy closed environment other species, various algae and cyanobacteria are two obvious choices will tend be able to out-compete the plants, at least for a time.

I would say that greaser84s answer was short and concise, Solcielo lawrencia and Hoppys also correct.

691175002 is correct as for as it goes since no matter how much relocating, even plants that can, cannot for long in a closed environment.

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post #10 of 26 (permalink) Old 09-16-2014, 01:44 PM Thread Starter
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Quote:
Originally Posted by greaser84 View Post
Are we talking dosing is the one and only source of KH2PO4?
No I never said that. Question is what happens once you stop dosing P04?

Quote:
Originally Posted by Solcielo lawrencia View Post
If you stop dosing an essential nutrient like P or K, the plant will stunt and algae will take over.
Question is what happens once you stop dosing P04? It might be true. However....

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Originally Posted by 691175002 View Post
According to deficiencyfinder, the plants will scavenge their oldest leaves for phosphorus. New growth will appear normal, but old leaves will quickly die.
Perhaps..

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Originally Posted by Diana View Post
However, P is in reasonable supply in fish food, so your plants might be just fine if you are feeding fish or shrimp in the tank.
Then again do we have to dose extra P for healthy growth and to keep algae in bay.

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Originally Posted by JoeRoun View Post
While it is true some plants scavenge themselves for nutrients and we could go through a whole list of alternate sources of every nutrient, and assuming JoraaN is an honest person asking an honest question.
Honest.....?? Its just a simple question where I see no reason to lie....

Quote:
Originally Posted by JoeRoun View Post
The result in a closed aquatic environment of the sudden removal of two major nutrients is going to be severe limitation of growth.
Perhaps....Again Question is what happens once you stop dosing P04?

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post #11 of 26 (permalink) Old 09-16-2014, 02:39 PM
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Phosphate Is essential. So it depends on whether or not there is enough phosphate to meet the need. If there is not, then the deficiency will show itself as stunted growth and discoloration.
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post #12 of 26 (permalink) Old 09-16-2014, 03:33 PM
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post #13 of 26 (permalink) Old 09-16-2014, 06:45 PM
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Quote:
Originally Posted by Joraa View Post

Then again do we have to dose extra P for healthy growth and to keep algae in bay.

That is a question we cannot answer for you. Is it possible you have enough P from fish food (and thus fish waste) alone? Yes. There are low tech purists out there that add nothing but light and fish food. If done carefully, this can be all you ever need.

Is it possible you need more than your fish food can provide alone? Yes. Given the number of people adding PO4 fertilizers (KH2PO4 or otherwise) to their tanks, this seems to be common, particularly in the high-tech end where nutrient use is quite high. (edit: yes, I know you specified high-light, I wanted to illustrate the range of possibilities, low-tech to high-tech.)

Getting a solid answer depends on a number of hard-to-measure things. You'll have to experiment with your tank, as the answer is going to be different from tank to tank. The same holds true for nearly every nutrient in the planted tank. There's rules of thumb out there, but if you want exact need levels, that takes personal experimentation with your specific tank conditions.

Fish food adds PO4. But even the simple question of how much total PO4 you are are adding depends on how much fish food you add, and what kind of food (different kinds have different concentrations of PO4). This is relatively easy to measure, but takes some calculating.

How much of that PO4 makes it to the plants is harder to quantify.
The tank inhabitants will eat some or all of the food. Of whatever the inhabitants consume, they'll use some of the phosphorus, and excrete as waste the rest. How much they use vs pass depends on things like breed, health, is it growing, and even how much it is being fed. Assuming you remove the inhabitants when they die, the PO4 they use is never released to the water column.


Any overfeed not eaten by the inhabitants is comparatively easy to account for, as it will eventually rot and make it straight to the water column. However, that involves knowing how much isn't being eaten, which might vary from day to day.

Of course, adding vacuuming, water changes, etc, removes some of this PO4, just to add a few more variables.

Last edited by mattinmd; 09-16-2014 at 06:47 PM. Reason: caveat added
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post #14 of 26 (permalink) Old 09-16-2014, 07:02 PM
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Quote:
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Quote:
Originally Posted by BruceF View Post
Phosphate Is essential. So it depends on whether or not there is enough phosphate to meet the need. If there is not, then the deficiency will show itself as stunted growth and discoloration.
Both of these are the best answers you are going to get.

You are asking a loaded question that nobody could possibly give a sweeping general answer to. In no situation can someone say with 100% certainty what will happen if you stop dosing KH2PO4 in any tank

If your PO4 in the water column is enough to sustain your plants growth given all the other factors then yes - you can stop dosing PO4 and nothing will happen. However this is not always going to be the case and will vary greatly depending on many variables. There is no 1 answer to this without asking 100 more questions... Totally depends on the tank / water parameters you are going to stop adding KH2PO4 to... MOST of the time KH2PO4 is the main source of PO4 in a fert regimen and plants will obviously show PO4 deficiencies if you stop dosing it and your tank runs out of PO4. Again this cannot be said true for all circumstances.

IMO just dose all macro/micros in abundance so that none can be limiting factors (this is why EI works so well as a starting point). Makes it way easier. Don't know why you would choose not to dose KH2PO4.


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Last edited by klibs; 09-16-2014 at 07:17 PM. Reason: asdfasdfsdf
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post #15 of 26 (permalink) Old 09-16-2014, 07:15 PM
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The water from the tap can also contain enough phosphate that adding it is not necessary.
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