Help me to understand Redfield Ratio

[potatocouch]

So this is Redfield ratio:

Are we aiming for the yellow cells there?

So whatever in yellow cells, the lower the number the better it is?

So if I take an example of 10 (in yellow), the perfect balance to achieve this is by 10 ppm of No3 and 1.5 ppm of Po4?

But I think SPS will suffer in this condition.

So for mixed reef tank (SPS, LPS & softies), what balanced ratio of No3 and Po4 should we be aiming for? would it be fair to say since SPS is better with No3 < 5 ppm then the balanced ratio would be:

• No3 2.5 ppm & Po4 0.3 ppm.
• No3 2.5 ppm & Po4 0.2 ppm.
• No3 1 ppm & Po4 0.1 ppm.

?

Is that correct?

 

[Randy Holmes-Farley Verified Community Expert]

I do not think that chart has any relevance to reef tanks, and definitely I do not agree with the color coding.

Here's a copy and paste from a previous thread where someone posted it:

FWIW, I found that table by image search, and I just do not think it is supplying info the way folks may interpret it.

This blog discusses it in the context of freshwater planted aquaria, where the goal is to provide optimal inorganic nutrients to keep the plants thriving, and when they are thriving, this author believes there is less chance for problem algae in competition with the plants.

http://www.aquascaping-blog.com/157/redfield-ratio

But, IMO, folks should not take away the idea that keeping a special balance of nutrient levels (especially when both are elevated) will reduce the chance for problem algae in a reef aquarium unless those nutrients are being used to drive a large amount of growth of something else, and that something else is outcompeting the problem algae for some other nutrient (such as iron, CO2, etc.).

 

[Adam Obenauf]

The chart is simply trying to illustrate to keep the NO3O4 ratio between 10:1 and 20:1. The ratio between the two helps to determine what the dominant species of algae is but as Randy said it won't necessarily reduce overall algae growth.

 

[potatocouch]

No problem .. thanks for clarifying that @Randy Holmes-Farley

Thanks @Adam Obenauf

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome

Happy Reefing.

 

[Down Under]

So this is Redfield ratio:

Are we aiming for the yellow cells there?

So whatever in yellow cells, the lower the number the better it is?

So if I take an example of 10 (in yellow), the perfect balance to achieve this is by 10 ppm of No3 and 1.5 ppm of Po4?

But I think SPS will suffer in this condition.

So for mixed reef tank (SPS, LPS & softies), what balanced ratio of No3 and Po4 should we be aiming for? would it be fair to say since SPS is better with No3 < 5 ppm then the balanced ratio would be:

• No3 2.5 ppm & Po4 0.3 ppm.
• No3 2.5 ppm & Po4 0.2 ppm.
• No3 1 ppm & Po4 0.1 ppm.

?

Is that correct?

That is correct. We have found 0.3 po4 is the bottom line comprble to no3 up 4.5. The actual po4 levels from the original were a little higher due to the presence of photoplankton. This was one of the many modelling exercises we critiqued back in the day at the marine institute. Mind you back in the 80s we only had wild caught specimens. I believe the frags are somwhat more robust. And thx for the feed back. Much appreciated.

 

[Randy Holmes-Farley Verified Community Expert]

That is correct. We have found 0.3 po4 is the bottom line comprble to no3 up 4.5. The actual po4 levels from the original were a little higher due to the presence of photoplankton. This was one of the many modelling exercises we critiqued back in the day at the marine institute. Mind you back in the 80s we only had wild caught specimens. I believe the frags are somwhat more robust. And thx for the feed back. Much appreciated.

Welcome to REEF2REEF!

Just to clarify, are you saying you generated that color coding?

What was the basis for the claims about little algae down the middle?

It doesn’t seem sensible to me that algae will be deterred just by a ratio of nitrate to phosphate if it has plenty of both.

 

[Dan_P]

So this is Redfield ratio:

Are we aiming for the yellow cells there?

So whatever in yellow cells, the lower the number the better it is?

So if I take an example of 10 (in yellow), the perfect balance to achieve this is by 10 ppm of No3 and 1.5 ppm of Po4?

But I think SPS will suffer in this condition.

So for mixed reef tank (SPS, LPS & softies), what balanced ratio of No3 and Po4 should we be aiming for? would it be fair to say since SPS is better with No3 < 5 ppm then the balanced ratio would be:

• No3 2.5 ppm & Po4 0.3 ppm.
• No3 2.5 ppm & Po4 0.2 ppm.
• No3 1 ppm & Po4 0.1 ppm.

?

Is that correct?

I can grow algae quite well with any of the ratios on this chart except where there are zeroes. What we keep forgetting is that controlling algae growth in aquaria is more than tweaking nutrient levels.