Redfield ratio calculation - help?

[JohnnyTabasco]

Hello. I'm trying to figure out how this (see img) is calculated...
I know there is mixed feeling about the redfild ratio but Richard Ross seem to know what he is talking about.
I just want to check out if the theory holds up.
Any way - I would be happy if any one know what the formula for this is.

 

[Randy Holmes-Farley Verified Community Expert]

I'm not sure what Richard says, but the Redfield ratio should neither be a dosing ratio nor the desired ratio in the water (IMO). It is the ratio of N to P in phytoplankton tissues (and hence an uptake ratio for them only), but there are plenty of unbalanced uses of these nutrients in reef tanks, such as denitrification which uses a lot of nitrate and not much phosphate.

That said, I'm not sure what you are trying to check out. The calculations on that table?

The Redfield Ratio is just the ratio of N to P in moles. To get moles from phosphate, divide the weight based concentration, (ppm or mg/L) by 95 (g/mole) and the nitrate concentration in the same units by 62 (g/mole).

For example, take the entry at 50 mg/L nitrate and 0.01 mg/L phosphate.

50/65 --> 0.77 N
0.01/95 --> 0.0001 P

N/P --> 0.77/0.0001 --> 7315

 

[JohnnyTabasco]

Thanks for the help with calculation.

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy Reefing. :)

 

[Juan Andrés Botero R]

You can find it here:
https://buddendo.home.xs4all.nl/aquarium/redfield_eng.htm#stock

 

[Reefahholic]

So it’s 2022. What is the redfield ratio now! LOL

 

[Dan_P]

You can find it here:
https://buddendo.home.xs4all.nl/aquarium/redfield_eng.htm#stock

Thanks for posting the link.

This information has not persuaded me from thinking that the use of the Redfield ratio in aquarium maintenance is useless.

 

[ReefGeezer]

Refields is informative, but it does not apply across all organisms. As Randy said, it is not a ratio that exists or even should exist in the water column. I'd also point out that much of the N used by the organisms is not measurable inorganic nitrate. Many organisms will use ammonia or get their nitrogen from organic compounds.

Edit: Organic Compounds not "Inorganic"

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for posting the link.

This information has not persuaded me from thinking that the use of the Redfield ratio in aquarium maintenance is useless.

No.

FWIW, it isn't even talking about marine systems.