The Redfield Ratio

[Biulu]

I found this very interesting article about the relationship between potassium, nitrate and algae in your tank. It is based on experiences of champions of the Dutch Aquarium Association. This is the link: http/www.xs4all.nl/~buddendo/aquarium/redfield_eng.htm

 

[SuperColey1]

I think the redfield is one of TB's pet hates Pretty much like any other 'mega lean' dosing strategy in that it can be such a pain, testing constantly, adjusting etc.

It is based on a proprtion that if you have X amount of N then you need X amount of P. too little P and you get green algae and too much then you get blue etc.

You then change the water to 'dilute' the P in the water and then add N to counter (or vice versa.)

The problem with this is that there are huge swathes of us with extreme differences to the 'ideal' ratio as shown in the chart on the page you link to which have no such problem therefore disproving the theory.

For example:

If I tested my water (which I don't and can't as I have no P test kit) and found my P was too high then the advice from the redfield tribe is to change water immediately.

Hmmmm. Here is a problem. Living in rural agricultural Lincolnshire changin water is not going to reduce my P!!! If anything it will increase it!!!

Counter that with N then. Hmmmm I don't want to be adding 50ppm tnitrate to counter the P in the tap do I? I don't think so.

No water changes? I don't do any!!!

Even eith high P I have never ever seen Blue green algae when I did changes or now with no changes. One of those algaes I have never encountered

Bang goes the theory? IMO yes.

I wouldn't want people to start getting excited about the redfield ratio. It isn't going to cure your algae. More likely is that by using the ratio guide they altered something else and that 'cured' their tank.

Maybe Tom will come in on this thread and explain in more knowledgable detail but I predict he will say:

All it is trying to do is limit P and we all know where that discussion will lead

AC

 

[ian]

didn't Redfield do most of his testing of Marine water?

I'm the same a Supercoley and live in rural Lincolnshire and i add 'P' and have no probs with alage.

 

[RadaR]

The Redfield Ratio is ridiculous for planted tanks. Plants dont care about ratios. They just want enough of the nutrients. Limiting P to reduce algae is halarious and completely flawed.
And yes, I believe it was done for marine algae.

 

[lljdma06]

The Redfield Ratio is ridiculous for planted tanks. Plants dont care about ratios. They just want enough of the nutrients. Limiting P to reduce algae is halarious and completely flawed.
And yes, I believe it was done for marine algae.

Redfield what?

That's what I have to say about it...

 

[plantbrain]

I do not hate RR, I just have a very different understanding about it than Charles does.
He still has never gotten back about the error with atomic vs mass ratios. RR is an atomic ratio, not mass, thus the ratio of N is off by about 2.2x.

RR should still provide folks with betetr results than dropping N or P to near zero of strongly limiting conditions.
But it does this independently of the ratio itself. It's more accurate to consider Liebig's law of the min when lookign at plant growth and horticulture, since this is what we are doing, not trying to outwit algae or limiting them. Algae have an order or two magnitude less than plants to limit them, so that's not going to work out well, the approach suggested by Charles is more about the plant needs that yield the results, not limiting or managing algae directly.

I have a ratio of 4:1 N

No issues on a dozen tanks

Probably not anything to do with the ratio.
The dosing is 15ppm NO3 and 5ppm PO4 3x a week.
I sell about 400-500$ a month worth of plants, and 100$ worth of RCS's from this one tank, and I have 5 more aquariums.

To me, that's better than any prize or title.


Regards,
Tom Barr

 

[Biulu]

Interesting. Can you elaborate more on Liebig's law?