Balancing nutrients

[ichthyoid]

Below is an interesting article I found about the importance of maintaining a balance of nutrients in reef aquaria, and the effect it has, especially N : P ratio. Take a look at the chart in the article -

The Redfield Ratio - Balancing Nutrients in a Saltwater Aquarium

If you have an 'unbalanced' saltwater tank, you may need to balance your nutrients. Find out how the Redfield Ratio can help.

www.thesaltyside.com

 

[Wmb0003]

I have seen this ratio before and worried about my nutrients because my nitrates are much higher than phosphates. But luckily I don’t have an algae problem, I am trying to lower my nitrates to get my ratio to the desired level.

With how easy GFO can remove/lower phosphates, I would think a lot of people have this ratio out of whack with nitrates much higher than where there phosphates should be(like my current situation). I would be interested to see people’s experience with the ratio out of whack with higher phosphates.

 

[ichthyoid]

If you follow the chart, low nitrate with high phosphate should lead to blue-green algae blooms (Cyanobacteria). They flourish under these conditions because they utilize inorganic nitrogen including N2, so can out-compete other algae.

Under the opposite conditions of high NO3 and low phosphate, green algae should thrive. To the point of phosphate dropping below 0.1 and becoming limited.

As mentioned in the article, it may be difficult trying to balance N : P ratios using hobbyist grade tests. As most aren’t accurate enough. Also, the tests we have only measure inorganic forms. Both nitrogen and phosphorous also occur in organic forms as well. So, we really can’t be sure without lab grade testing.

 

[timeconsumer]

I have a few things about the Redfield Ratio stuff that irks me.

First off, the 16:1 N : P ratio that Redfield noted was measured in molar units, so the ratio of one atom to another. In the hobby we are measuring ppm of nitrate and ppm phosphate which take the mass of the molecule into account. If Redfield had been measuring in ppm he would have measured a ratio of 24:1. So right off the bat hobbyists are using the wrong numbers entirely.

Second off, Redfield's ratio was about the ratio of nutrient uptake in phytoplanktons. It wasn't a measure of the nutrient levels of water, or of the best environment for cyanobacteria to live in, or for macro algae to grow in. All he did was collect samples of plankton from the surface waters around the world and measure the ratios of C, N, and P atoms. I think people are drawing conclusions (based on the wrong numbers) that this study really was never about.