Redfield ratio quetion

[ddc0715]

The Redfield Ratio is on my mind an I found Randy's formula to calculate the ratio of N to P in moles

Here's my numbers
20 mg/L (salifert kit) nitrate and 2 mg/L phosphate.(salifert kit)

20/65 --> 0.307 N
2/95 --> 0.021 P

N/P --> 0.307/0.021 --> 1461

However I'm not sure what this is telling me about my tanks ratio, can some aid me here. My tank is crystal.

 

[tsouth]

In nature, corals feed on phytoplankton, even the corals who live in symbiosis with zooxanthellae. When they digest the phytoplankton, they get C(arbon), N(itrate) and P(hosphate) in the Redfield Ratio or close to it. Corals then use the C, N and P they have consumed to build up their tissue. So it's a constant cycle that aids in helping corals thrive. We supplement our tanks with additives and foods in order to keep these levels elevated, and most importantly, balanced.

The Redfield ratio essentially says that you should have 16 parts of nitrate, to 1 part of phosphate right? So it would look kind of like this:

1 P : 16 N
0.1 P : 1.6N
0.01 P : 0.16 N

In your case you have

0.021 P, and the redfield equivalent would be 0.336 - and you stand at 0.307. Pretty good!

Fwiw, many advise not to chase numbers, especially if your tank is looking most excellent. Sounds like you're on a good track, keep it up.

 

[ddc0715]

thanks, i was not sure if it was a good place to be thanks for confirming

 

[taricha]

But if you actually have 2ppm PO4 (2mg/L), then that's like 20 to 50x higher than what people aim for.

 

[ddc0715]

I have heard, an read the same. But I have no algee issues and my tank has (knock on wood) prestine clarity. An the ratio is solid. Makes u wonder. Research is more like GUIDELINES. IMO. LOL

 

[Reef and Dive]

It serves as a guide only. Specially to understand when you have problems.

I would not consider salifert phos a good reference to calculate the ratio...

Some discussion on that topic here:

https://www.reef2reef.com/threads/redfield-ratio-revisited-–-what-are-we-doing-wrong.742503/

 

[dimsim]

My understanding is that redfield ratio represents the averaged N : P uptake ratios of marine algaes/photoautotrophs; not by extension some parameter of NSW that need be 'chased' or replicated. Although I guess in captive/closed reef systems it likely has some relevance on managing facultative microbial... stuff (dinoflagellates/cyano etc.)... Sorry not the resident microbiologist here, just rambling about things I vaguely understand haha.

 

[Dan_P]

The Redfield Ratio is on my mind an I found Randy's formula to calculate the ratio of N to P in moles

Here's my numbers
20 mg/L (salifert kit) nitrate and 2 mg/L phosphate.(salifert kit)

20/65 --> 0.307 N
2/95 --> 0.021 P

N/P --> 0.307/0.021 --> 1461

However I'm not sure what this is telling me about my tanks ratio, can some aid me here. My tank is crystal.

The Redfield ratio has never been demonstrated to be useful for aquarium management. The ratio is telling you absolutely nothing about your system.

 

[ddc0715]

Tells me nothing? Not sure I agree with that, but Maybe. if it's has no usefulness, why is there SOOO much info out there about it; an how it relates to our tanks. Also I do not chase, or strive to achieve the ratio with my dosing or testing, I just tested the other day and wondered what my ratio was since I knew the 2 wps that were use to determine it.

 

[Deep]

Tells me nothing? Not sure I agree with that, but Maybe. if it's has no usefulness, why is there SOOO much info out there about it; an how it relates to oio,ur tanks. Also I do not chase, or strive to achieve the ratio with my dosing or testing, I just tested the other day and wondered what my ratio was since I knew the 2 wps that were use to determine it.

Redfield ratio is the ratio for chemical elements present in the average Phytoplankton bio-mass. It is not applicable to anything other than Phyto. Sure, there might be other ratios for other animals ( corals etc), but it is not the redfield ratio.

 

[nereefpat]

if it's has no usefulness, why is there SOOO much info out there about it; an how it relates to our tanks.

I think it's because some people got confused when they originally read about it, thinking it applied to a ratio of N&P we should try to keep in our aquariums, when it has nothing to do with that.

 

[taricha]

Some tanks quickly consume any measurable NO3 and have "normal" PO4 of ~0.05 for an N/P ratio of zero
Some tanks push for barely detectable PO4 <0.03 and dose NO3 to 5 ppm or so for a N/P ratio of 250+.
The OP has something very near 16 N/P but a PO4 or 2.0ppm that nobody would say is a "good target" for others to aim for, but @david campbell has a great looking tank.

There are people with all those cases who say that their system is stable and their corals are happy.
So if a target number is "16", but tanks look equally good (or bad) at 16, or zero or 250+, then would be fair to say it has very little predictive value.

(Some would say "no predictive value" but I would argue the tanks at "zero" and at 250+ N/P are prone to different nuisances, so that is a prediction. Just not one about coral health.)