# Phosphate and Nitrate ratio?



## JinxXx0085 (Jul 2, 2005)

Howdy there!

I'm not sure if I remembered correctly... phosphate and nitrate has to be in a certain ratio to keep algae under control?

I just did a WC today and tested the tank water. 
I found out that I had 5ppm Phosphate and around 10ppm Nitrate (I dosed nitrate). 

I dose my 29g using EI method. It has 110 watts over it.
If you need more info, ask away.


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## trenac (Jul 16, 2004)

The ratio is 10ppm of nitrates to 1ppm of phosphates. So you either need to raise your nitrates or lower the phosphates. I think I would choose to lower the phosphates.


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## hoppycalif (Apr 7, 2005)

I think the need for a ratio between nitrate and phosphate has not been universally accepted. For sure you do need some phosphate, and you need a lot more nitrate than phosphate. Many of us dosing EI method dose closer to 1 to 4 than 1 to 10. And, if we run into green spot algae we tend to increase the phosphate, while if we run into blue green algae we tend to increase the nitrate. My opinion, which also is not universally accepted, is that you shouldn't even attempt to use hobby test kits to determine how much of any fertilizer to dose.


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## Ajax (Apr 3, 2006)

hoppycalif said:


> My opinion, which also is not universally accepted, is that you shouldn't even attempt to use hobby test kits to determine how much of any fertilizer to dose.


Why is that?


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## houseofcards (Feb 16, 2005)

hoppycalif said:


> I think the need for a ratio between nitrate and phosphate has not been universally accepted. For sure you do need some phosphate, and you need a lot more nitrate than phosphate. Many of us dosing EI method dose closer to 1 to 4 than 1 to 10. And, if we run into green spot algae we tend to increase the phosphate, while if we run into blue green algae we tend to increase the nitrate. My opinion, which also is not universally accepted, is that you shouldn't even attempt to use hobby test kits to determine how much of any fertilizer to dose.


I couldn't agree more concerning test kits. It's almost impossible with any certainty to really know how much no3 and po4 you have using most standard kits. Remember it's suppose to be an "Estimative Index" so you could be off by a factor of 2 and you'll still be within range. I could tell you that I dose 10 to 1 (no3 to po4) and have not had any problems. I really have no idea what my levels are.


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## banderbe (Nov 17, 2005)

Ajax said:


> Why is that?


I agree w/ him. Test kits will almost always lead you down the path to problems.

It's much easier to start with a baseline of fertilizer so you know the ppm you're aiming for given your volume of water, and watch the plants.

I haven't used a test kit of any kind on my tank in many months. I have no idea what my ph, KH, GH, nitrates, phosphates, anything are... Totally flying blind. Although I can guess about what my KH and GH probably are since I use RO water.


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## Salt (Apr 5, 2005)

There is absolutely nothing wrong with using test kits. In my own opinion, advising people in a terse manner that using them will cause them problems is misleading advice.

For example, if you're trying to grow certain plants and are unsuccessful, and you know that those plants tend to grow better in lower kH and magnesium levels, you test your water and find high kH and high magnesium. You lower it using RO or distilled water, and the plants grow better.


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## banderbe (Nov 17, 2005)

Testing KH and responding accordingly is a far cry from testing NO3, PO4, or god forbid Fe, and adjusting one's dosing according to the results of a test kit.

Thread after thread will show a person testing for nitrates, convinced they have very high levels of nitrates, then taking all sorts of extreme measures to try and lower the nitrates, only to bottom out on nitrates and wind up with unhappy plants and algae.

I won't hesitate to recommend people to trust their plants instead of test kits. Whether anyone listens is up to them. I'm largely parroting the advice of more seasoned experts.


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## houseofcards (Feb 16, 2005)

Salt said:


> There is absolutely nothing wrong with using test kits. In my own opinion, advising people in a terse manner that using them will cause them problems is misleading advice.....


On some test kits it's almost impossible to tell the difference between 20ppm and 80ppm of nitrate. So if one is to interpret the 20 as an 80 or vice-versa then that could definitely lead to problems. I thought this thread was about po4 and no3 the example you gave was about KH and Mg.

If one is dosing with the EI method (which this aquarist is) and working within the ranges and then refreshing their system with a 50% water change weekly they are much better off watching their tank and fine-tuning things then trying to decifier the shade of orange on a test kit. This is My-Humble-Opinion of course.


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## Laith (Sep 4, 2004)

This is an ongoing debate  . Myself I rarely test unless I see that something is out of balance. Or just because I get curious and can't help myself!  

However, when I do test, I need to trust the test kit to a certain extent. So the moral of the story is:

Regulary test/calibrate your test kits with a known concentration of whatever you're testing for (and if you really want to be sure, test the test kit with several different concentrations as many test kits will measure well at low concentrations and be completely off at higher concentrations and vice versa). This is more relevant to NO3, PO4 and Fe tests than KH and GH test which in general are pretty reliable.

I have seen NO3 test kits measure high levels of NO3 in distilled water! And yes, I've even seen LaMotte test kits give incorrect results.

Yes, it is extra work. If you don't want to bother then don't trust your test kits and rely instead on how your plants look and how much of each nutrient you're adding and the frequency/percentage of water changes you're doing...


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## Glouglou (Feb 21, 2006)

*The Redfield ratio...*

You can read interesting stuff about control of algae in freshwater with the Redfield ratio (ratio nitrate/phosphate) at this adress:

http://www.xs4all.nl/~buddendo/aquarium/redfield_eng.htm

*And I really feel I want to say the words, the unholly, the terrible words...*

I'm using test kit and I love it...
:cheer2: :cheer2: :cheer2: :cheer2: :cheer2: :cheer2: :cheer2: :cheer2::cheer2:


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## houseofcards (Feb 16, 2005)

Well I guess it comes down to a comfort level. I soon realized that the test kits were making me fine-tune things, but I soon realized it was the test kits that needed fine-tuning. The EI ranges are pretty broad and most plants will live and grow nicely in those ranges assuming all their other needs are met. So if you love to play with your test tubes, who am I to stand in your way!


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## hoppycalif (Apr 7, 2005)

Different people find different aspects of this hobby to enjoy. I enjoyed the testing for awhile, until I got frustrated with it. I have always enjoyed DIY projects, even when they prove uneconomical, and they have almost always been so for me. But, now I want to minimize maintenance and enjoy the plants and livestock. Who knows what will rock my boat next year?


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## Edward (May 25, 2004)

A test kit _*'calibration'*_ procedure is about learning how to use the product properly. 

Funny is that people who use spoons instead of scales are the ones complaining about test kits being inaccurate?


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## Laith (Sep 4, 2004)

I use scales...


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## houseofcards (Feb 16, 2005)

_Funny is that people who use spoons instead of scales are the ones complaining about test kits being inaccurate_
Well I don't use test kits or scales and I'll tell you why. Test Kits are just to hard to interpret IMO and to use scales means your trying to hit a bullseye. Assuming we are talking EI then it's an "Estimative" Index and one could be pretty far off on dosing and still be within range especially since we are refreshing every week. If your using spoons aren't you "MICROmanaging your MACROS"


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## JinxXx0085 (Jul 2, 2005)

Interesting responses I've gotten! At the moment, my DIY CO2 wasn't working right due to a leak but I got that fixed... Maybe thats why the algae was unsightly lately.

*BUT* I still wanted to know if there were a certain ratio that is desireable I guess I've stumbled into a debate  Debate is good and fun! 

I recently tested my phosphate again and it is.... still 5 ppm
Nitrate.... less than 10ppm
I like testing just because it gives me an overall idea what is going on in my 29g as I'm still new at this.


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## Glouglou (Feb 21, 2006)

*Oh yes about that NP Ratio*

There is a very interesting link about that subject:

http://www.xs4all.nl/~buddendo/aquarium/redfield_eng.htm


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## Edward (May 25, 2004)

You can have 0.1 PO4 / 20 NO3 or 1 PO4 / 5 NO3, both works. Plants do not care about ratio.


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## Laith (Sep 4, 2004)

Edward said:


> You can have 0.1 PO4 / 20 NO3 or 1 PO4 / 5 NO3, both works. Plants do not care about ratio.


I agree. It's more important to not bottom out on either of them than it is to try to keep them at a specific ratio. I've had tanks with 5mg/l of PO4 and 20mg/ NO3 and tanks with 2mg/l PO4 and 40mg/l NO3 and both have done very well.

The Redfield Ratio is based on the N composition of Phytoplankton in the ocean. I'm not too sure how the leap was made from marine phytoplankton to freshwater higher "level" plants...

Here's an interesting extract from an article from researchers at Georgia Tech (http://gtresearchnews.gatech.edu/newsrelease/nutrient.htm). It still relates to phytoplankton, but describes how the ratio changes depending on availability of nutrients:

"Under two extreme conditions - one with few resources because of increased competition and the other with abundant nutrients - researchers determined the optimal strategies that phytoplankton use to allocate the cellular machinery - namely ribosomes and chloroplasts -- for nutrient uptake. Ribosomes assemble two proteins that take up nitrogen and phosphorus. Chloroplasts gather energy from the sun.

"When competing to the very end, then the optimal strategy has a lot of resource acquisition machinery, but not much assembly machinery," Klausmeier explained. "In that case, there aren't many ribosomes, and therefore not much phosphorus. So if you have a small amount of phosphorus, you have a high N ratio. This strategy is best for competition to equilibrium.

"In the other scenario, where nutrients are very available, you have a lot of ribosomes. Then you have a lot of phosphorus and therefore, a low N ratio. This is optimal under exponential growth conditions," Klausmeier added.

Given these optimal strategies, researchers were able to determine the N needs of species competing at the extremes. "These two scenarios set the endpoints of what happens in reality," Klausmeier explained. "In the real world, it's a mix of conditions."

From a literature review earlier in the study, they found that N ratios among different species vary from 7:1 to 43:1 - with one oddity requiring a 133:1 ratio. Results from modeling the optimal strategies mirror this range of ratios, Klausmeier said, in contrast with the long-accepted constant ratio of N in the ocean. "


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## marvelous (Jul 29, 2006)

*My two cents*

I have a 75 gallon heavily planted with a little bga that I am going to get some flag fish for and some hair algae - but nothing major. My NO3 and PO4 read absolutely zero with my test kits. Ironically my plants are doing very well in the "absence" of these key nutrients and I have minimal algae. So are my plants thriving without these nutrients or are my test kits that far off? I fertilize with Excel 3x/week - NPK 3x/week and Flourish micros 3x/week. Or perhaps am I not fertilizing enough? To put it in perspective I added my regimen of macros and micros and NO3 and PO4 still read zero - also Excel. I have to believe that test kits are very unreliable and provide a general basis at best - IMO. Besides - some fish eat algae as their staple diet. The next time you're in the Amazon stick your head in the water and see how much algae is present and see how the plants are thriving!? IMO if you have "too much" algae and your plants are still thriving put more algae eating fish in the tank - seems natural to me. I know this seems a little remedial, but algae is natural and it seems logical to provide a natural solution to its existence if in excess. I have read the specs on some of Amano's tanks and most of his say fertilization is unnecessary in some of his tanks. Perhaps I am reading this wrong. Any ideas? "balanced aquarium".


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## hoppycalif (Apr 7, 2005)

marvelous said:


> I have a 75 gallon heavily planted with a little bga that I am going to get some flag fish for and some hair algae - but nothing major. My NO3 and PO4 read absolutely zero with my test kits. Ironically my plants are doing very well in the "absence" of these key nutrients and I have minimal algae. So are my plants thriving without these nutrients or are my test kits that far off? I fertilize with Excel 3x/week - NPK 3x/week and Flourish micros 3x/week. Or perhaps am I not fertilizing enough? To put it in perspective I added my regimen of macros and micros and NO3 and PO4 still read zero - also Excel. I have to believe that test kits are very unreliable and provide a general basis at best - IMO. Besides - some fish eat algae as their staple diet. The next time you're in the Amazon stick your head in the water and see how much algae is present and see how the plants are thriving!? IMO if you have "too much" algae and your plants are still thriving put more algae eating fish in the tank - seems natural to me. I know this seems a little remedial, but algae is natural and it seems logical to provide a natural solution to its existence if in excess. I have read the specs on some of Amano's tanks and most of his say fertilization is unnecessary in some of his tanks. Perhaps I am reading this wrong. Any ideas? "balanced aquarium".


My first idea is the obvious one. If you take a tank full of water, add some NO3 and PO4, then measure how much is in the water, and your test kit says "none", your test kit is wrong. So, if you want to actually measure how much of any fert you have in the water, the first step has to be callibrating the test kits you plan to use.

My second idea is that each of us has to decide what we want to see growing in our tank. Those of us who don't mind if a bit of algae grows, as long as it remains a bit, have more flexibility in how we handle algae than those who do mind seeing even a spot of algae in the tank. Neither group is right or wrong, just different.


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## Zapins (Jul 28, 2004)

"You can have 0.1 PO4 / 20 NO3 or 1 PO4 / 5 NO3, both works. Plants do not care about ratio."

Soo what about extremes like 8ppm Po4 to .2 ppm nitrate? Plants don't care about ratio?


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## Laith (Sep 4, 2004)

Zapins said:


> ...
> Soo what about extremes like 8ppm Po4 to .2 ppm nitrate? Plants don't care about ratio?


I think the problem here would not be one of ratio but one of nitrate deficiency, leading to an imbalance in nutrients, leading to algae, leading to the following possible (and incorrect) assumptions:

- PO4 causes algae...
- Ratios are important...

...


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## Zapins (Jul 28, 2004)

...haha. 

Maybe .2ppm was extreme, but still if it is kept constant at that low level... or even at 5ppm. Still no problems? I think the consensus so far is you need to have more NO3 than PO4, which sounds like the beginnings of a ratio to me


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## hoppycalif (Apr 7, 2005)

I don't think plants take up nutrients in proportion to their concentration in the water. So, if I'm right, it doesn't matter if NO3 is in greater concentration than PO4, only that both be available in adequate concentration.


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## Zapins (Jul 28, 2004)

Maybe not set in exact ratios, but there are definitely certain general ratios that minimize problems in tanks. 

After all if the ratio was as flexible as you say, then we would see more crazy extremes like 8Po4 to 5No3. I think it would be interesting to test it out.

I will set up some tests later this year and let you know what I find.


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## Edward (May 25, 2004)

The problem is not with the test kits. The problem is with people dumping spoons of dry chemicals in their aquariums and then testing 90 ppm NO3. Wow - it must be a bad kit!


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