How do high Phosphate and Nitrates and vise versa offset eachother? And how do you achieve equalibrium between the two?

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LRT

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Looking to wrap my head around the chemistry between the two.
Recently overdosed my Nitrates with bad test kit to astronomical high numbers undetectable on Red Sea chart.
At the time I was showing .025 Phosphates. Idk what Nitrates actually where as test kit was faulty.
Got my Nitrates down to 15-20ppm but now Phosphates are zeroing out.
Should I be running phosphates higher since nitrates are higher and nitrates are depleting phosphates?
Does higher or lower alkalinity have anything to do with this equalibrium?
Is there a formula that calculates what phosphates should be to nitrates?
Has anyone written a reef chemistry book for dummies yet? If not I'm sure it would be best seller if it already isnt.
 

Raege

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Redfield ratio is about the relationship nitrate phosphate at 16 to 1 Its a crazy holy grail number to chase considering accuracy of our test kits and water volumes we have but gives something to go by and reference. Lots of different numbers folks shoot for depending on individual tank and what your filling it with. 5 nitrates and .004 Pho’s gif dole while others have nitrates in 20 and higher and po4 much higher’ I think you need to keep pho’s up for consumption of no3 how high no clue Do know zeroing out can cause issues
Let’s get some squad opinions
#reefsquad
 

GoVols

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I think you need to keep pho’s up for consumption of no3 how high no clue Do know zeroing out can cause issues
Let’s get some squad opinions

Yep

As far as alk, the conversion of ammonia to nitrites to nitrates can draw down alk, but if you can get your nitrates to gas off by denitrification, that would replenish the drawn down alk.

You can also be carbon deficient as a third aspect of the process.
 
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1mbrews8

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I'd love to hear more on this topic too!

My nitrates are still around 100 via a salifert test, but the hanna handheld says 0 phos.

I've tried using a homemade phosphate reactor, but didn't seem to do anything... coral (most) seems ok, but worried :eek:(
 

Dan_P

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Should I be running phosphates higher since nitrates are higher and nitrates are depleting phosphates?

The PO4 level should reflect what your coral need. Keeping it at that level will also satisfy all other organisms’ need for PO4.

Does higher or lower alkalinity have anything to do with this equalibrium?

Alkalinity can increase as a consequence of nitrate consumption, but within the range of alkalinity levels required for healthy coral, alkalinity will have no detectable effect.

Is there a formula that calculates what phosphates should be to nitrates?

No. And the use of the Redfield ratio in this situation represents a misunderstanding of the science behind this stoichiometric ratio. Again, the focus is on what your coral need. It seems 0.03 ppm PO4 is the consensus level for coral, but some observe 0.1 ppm being OK too. Coral health has the last word. The same advice goes for nitrate levels.

Has anyone written a reef chemistry book for dummies yet? If not I'm sure it would be best seller if it already isnt.

Randy has published a series of articles on saltwater and reef water chemistry. They are comprehensive with references but very accessible. You can find them in the “stickies”.
 
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Randy Holmes-Farley

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Redfield ratios should not, IMO, be any sort of goal. Targhet both idnependently to desirable levels.

There is no reason to think that sub optimal levels of one (say, 200 ppm phosphate or 0.0001 ppm phosphate) "offset" suboptimal levels of the other (say,2000 ppm nitrate or 0.000001 ppm nitrate)
 

amazongb

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Redfield ratios should not, IMO, be any sort of goal. Targhet both idnependently to desirable levels.

There is no reason to think that sub optimal levels of one (say, 200 ppm phosphate or 0.0001 ppm phosphate) "offset" suboptimal levels of the other (say,2000 ppm nitrate or 0.000001 ppm nitrate)

I recall reading this advice from you when I first started in the hobby a few years ago, and follow it closely. My tank, for whatever reason, looks best at around 10-12ppm nitrates, and .08-.11 phosphates, so a keep it around there..i have no idea if it's close to redfield or not..
 

minus9

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I'm with Randy on this one. Target reasonable ranges for both and monitor coral health and growth. Also, not knowing the first part of the ratio makes the others pointless. Besides, it describes the ratio for phytoplankton, not zooxanthellae.
 
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LRT

LRT

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Redfield ratios should not, IMO, be any sort of goal. Targhet both idnependently to desirable levels.

There is no reason to think that sub optimal levels of one (say, 200 ppm phosphate or 0.0001 ppm phosphate) "offset" suboptimal levels of the other (say,2000 ppm nitrate or 0.000001 ppm nitrate)
Thanks for the reply Dr. Let me ask it a different way. Should I dose phosphates a little more until it stabilizes and stops zeroing out?
I'll be honest before my recent Nitrate overdose I felt like everything was fine. Alk was a little high around 11. Dunno where Nitrates where at as I had faulty reader with Phospahtes sitting at .025.
Some corals dont look as good as they did before Nitrate O.D. But I'm not sure if that's because of lack of phosphates in system.
I do trust salifert and red sea kits as of now they have been confirmed by lfs.
Heres my parameters as of yesterday:
Salitinity- 1.025
Cal- 416
Mag-1310
Nitrates- 15-20
Alk- 9.8
Temp- 77.1
Phosphates- Not detectable (salifert)
Trying to keep around .01- .03 but been a consistent battle last cpl weeks.
 

Zerobytes

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On my tank, if PO4 gets too high or NO3 gets too low things degrade. I don’t know the science involved and every rank is different but that’s what I’ve experienced. I try to keep PO4 around .05 and nitrates 10-15 ppm. I can tell by the corals when one or the other other is out of whack. if my PO4 goes up, I reduce feeding for a few weeks but sometimes I add some GFO. And sometimes I need dose NO3 to bring it up. It seldom gets too high on its own.
 

reefsofty

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I'd love to hear more on this topic too!

My nitrates are still around 100 via a salifert test, but the hanna handheld says 0 phos.

I've tried using a homemade phosphate reactor, but didn't seem to do anything... coral (most) seems ok, but worried :eek:(
your math is off. the high range is not 100, but 10 with sallifert.
 
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