Redfield Ratio

Picassoclown · Apr 8, 2023

Hello everyone. I am trying to understand the Redfield ratio. I currently have Phosphates at 0.21ppm, what would the ideal target be for nitrates? My nitrates are currently sitting at 8.5ppm as of this morning. I am battling Dinos at the moment and making some decent progress after having them for 5 months. I want to make sure I am getting these 2 components in line, as I think people vastly underestimate how important it is. My main objective is to fuel other algae growth to outcompete the Dinos. I have a yellowish-green algae now that is growing on my live rock that killed off the Dinos. Now I just have them left on my sand bed.

Thanks in advance!

Pntbll687 · Apr 8, 2023

100:1 ratio is usually the go to measurement when just comparing nitrates and phosphate. So I’d shoot for somewhere around 20 ppm nitrate if you keep phosphate at .2

Dburr1014 · Apr 8, 2023

Picassoclown said:
Hello everyone. I am trying to understand the Redfield ratio. I currently have Phosphates at 0.21ppm, what would the ideal target be for nitrates? My nitrates are currently sitting at 8.5ppm as of this morning. I am battling Dinos at the moment and making some decent progress after having them for 5 months. I want to make sure I am getting these 2 components in line, as I think people vastly underestimate how important it is. My main objective is to fuel other algae growth to outcompete the Dinos. I have a yellowish-green algae now that is growing on my live rock that killed off the Dinos. Now I just have them left on my sand bed.

Thanks in advance!

Redfield ratio means nothing.
PO4 at 0.21 you can keep NO3 anywhere from 2ppm to 10pmm, or as suggested, higher.
PO4, imo, is more important than the no3 level.

Edit: don't get hung up on a ratio just pick a Target and try to maintain.

redfishbluefish · Apr 8, 2023

REDFIELD RATIO - It's nice to know for the sake of general knowledge that there is a ratio of carbon, nitrogen and phosphate in living organisms. For marine algae, and I believe it was a particular phytoplankton, that ratio is one hundred and something:16:1 for carbon:nitrogen: phosphate, respectively (I can't remember the exact carbon number). The guy who discovered this was Redfield, so they called it the Redfield ratio. Note that this ratio is an atomic ratio. Other organisms and even other types of algae have different ratios. Now that you know all that, forget about it, because it won't help with your tank.

What you are measuring in your tank is not atomic numbers but molecular numbers. You're not measuring Nitrogen, but Nitrate; you're not measuring phosphorus, put phosphate. You could convert to the atomic ratios, but bottom line, it's not going to tell you much of anything. Just keep your nitrates and phosphate numbers in a concentration your corals like. Think of it as the Goldilocks Ratio....not too high, not too low, but just right.

Pntbll687 · Apr 8, 2023

Dburr1014 said:
Redfield ratio means nothing.
PO4 at 0.21 you can keep NO3 anywhere from 2ppm to 10pmm, or as suggested, higher.
PO4, imo, is more important than the no3 level.

Edit: don't get hung up on a ratio just pick a Target and try to maintain.

Agree with everything here.

I’ve found the getting nutrients higher to fight Dinos is “easier” with nitrates in the 20-30 range and phosphate in the .15-.3 range. Not because it’s some magical range, it just makes it so you don’t fall down to zero too quickly

teethdoctor23 · Apr 8, 2023

Agreed with everything posted here! You will see tanks that are successful with phosphates and nitrates off the charts! Most LPS and softies love dirty water, with stability SPS will love the nutrients as well. Aim for stability.

Picassoclown · Apr 8, 2023

WOW. Thanks for all the feedback so quickly! I just started dosing silicates to tackle the Dinos as nothing else has worked. I also started dosing Polyplab Genesis bacteria. I have heard it works wonders against Dinos, let's see what happens. Will Dinos eventually dissipate from the sand bed with elevated nutrients over time? The ones on the sand are such a pain to get rid of

ichthyoid · Apr 9, 2023

The Redfield Ratio is the recurring ratio of 106:16:1 of carbon to nitrogen to phosphorus (C:N-P) found in marine phytoplankton.

Two things,
First- it’s the ratio of elemental forms of carbon to nitrogen to phosphorous NOT the various organic & inorganic forms of carbon, nitrogen and phosphorous which are actually found. It’s important to note here that all we can measure with our cheap test kits is certain inorganic forms of molecules containing these elements. That can make a big difference mathematically, due to differing elemental and molecular atomic weights. Or stoichiometrically, as it’s called in chemistry. Follow others’ advice ^

Second- the ratio was observed in phytoplankton, NOT in sea water. If you research nutrient levels in reef environment waters and compare it to phytoplankton it’s pretty meaningless to us. Organisms, including phytoplankton, have the ability to regulate their internal chemistry vs what is in their surrounding environment. Within some limits of course.