What is your N/P ratio?

[WrasseyReefer]

I do not think it is desirable or even sensible for reefers to think of nutrient target levels as ratios. It just serves to lead to false conclusions.

It is never wrong, and usually far more informative to discuss the absolute levels of each.

For example, does it make any sense if N is very low, say, 0.001 ppm nitrate, for phosphate to also be very low, say 0.0001 ppm?

Makes sense.

 

[KrisReef]

My post regarding “high” was deleted as being not very family friendly. I was merely pointing out that the “high” phos and nitrate in these tests were probably not as high as I would consider high.

Guess in too innocent, or ignorant, hey ho

I appreciate your family hostile posting, presumably you appreciate wicked and thoughtful debate on the subject of ratios.

I had a similar experience recently and I don’t remember what I said to get the mods to erase my comment?

That aside, I have tried to understand the ratio debate and my nitrate is often zero even though I feed fresh seafood consistently. Phosphate is all over map and I remove it with liquid P killer every other day.

N for me is undefined as Zero/ N is.

 

[Randy Holmes-Farley Verified Community Expert]

Interesting. Would you mind sharing the Hans Werner posts you’re referring to? I’d like to learn more.

Here’s a paper that talks about the redfield ratio and how it indeed is the composition of these nutrients in phytoplankton but how the ratio is very similar in oceans.

https://www.science.org/doi/10.1126/sciadv.aaw9371

“In a seminal paper in 1934, Redfield proposed that the global spatial and temporal average C:N: P of POM (defined as the organic matter retained on 0.7-μm filters and composed mostly of phytoplankton cells) is constant and remarkably similar to the ratio of dissolved inorganic nutrients in the deep ocean, most likely as a result of the decomposition of POM into its constituents (5, 6).“

And I’m curious what your take is on this paper, since they did conclude that ratio does have an impact on coral health, growth, and bleaching. However, you’re saying you don’t think that ratios matter.

And yeah, 16:1 probably isn’t ideal anymore. I think it’s changed to 22:1 now. But yeah, I don’t know if there is an ideal since many people run their reefs at far from those ratios with much success. I’m interested in learning more about this topic.

Curious, where do you keep your nitrates and phosphates and where is your ratio at?

Redfield didn’t keep reef tanks and never suggested the ratio in seawater were targets.

Seriously, why not target the actual seawater values? I’ll tell you why: THEY FAIL. They are too low, for corals not getting lots of particulate matter.we learned this the hard way over many years.

So why take a half ways approach and think ratios are the key. No data at all supports ratios as opposed to appropriate absolute values.

 

[WrasseyReefer]

I think we can conclude this thread. It’s clear that ratios don’t matter. Thanks, everyone for sharing your feedback.

 

[revhtree Verified Admin]

My post regarding “high” was deleted as being not very family friendly. I was merely pointing out that the “high” phos and nitrate in these tests were probably not as high as I would consider high.

Guess in too innocent, or ignorant, hey ho

Not exactly sure what happened but this was brought to our attention and had been restored!

 

[gbroadbridge]

Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates - PMC

Enrichment of reef environments with dissolved inorganic nutrients is considered a major threat to the survival of corals living in symbiosis with dinoflagellates (Symbiodinium sp.). We argue, however, that the direct negative effects on the ...

www.ncbi.nlm.nih.gov

This paper is really interesting and has been discussed on R2R before, but I wanted to find out where people keep their N/P ratio. While we know that 16:1 is the ideal N/P ratio, it’s definitely difficult to attain and maintain, so we do our best to maintain our nitrates and phosphates at values that we think work best. I’m curious where other reefers tend to keep their nitrates and phosphates and where that lands their N/P ratio.

The paper basically shows that high nitrates/high phosphorous is ideal, but low nitrate/high phosphate “corals suggest that the N-limitation sustains a slower but chemically balanced growth while maintaining a functional photosynthesis.”

High nitrate/low phosphorous and low nitrate/low phosphorous “conditions were more susceptible to bleaching when exposed to heat stress and/or elevated light levels (Wiedenmann et al., 2013). The detrimental effects were linked to the relative undersupply with phosphorus that can result from the higher demand of the proliferating algal populations rather than to the high nitrogen levels.”

In the context of a reef tank ratios are just plain BS.

Normally promoted by folks looking for something to blame when they stuffed up.

 

[Timfish]

Yeah, super low ratios compared to what hobbyists likely keep in their tanks. It’s interesting.

Where do you keep your nitrates and phosphates, and where does that land your N/P?

Over the decades I've seen a wide range of ratios in my systems. What I aim for is PO4 between .03 mg/l and .3 mg/l. For nitrate below 5 mg/l.

FWIW .03 mg/l is the threshold level to prevent phosphorus limitation in corals, identified by researchers at Southampton University in England using corals maintained in an aquarium for about a decade. .3 mg/l is what corals are subjected to with upwelling in the ocean. .5 mg/l is acceptable as acros have been shown to incease growth up to this level. .9mg/l is the level teh Steinhart Aqaurium's ex situ sexually reproduced acro colonies are being grwon out with. Rich Ross's (who's part of the team at Steinhart) has his acro dominate mixed reef sitting at 1.8 mg/l, his tank can be seen at the beginning of his MACNA presentation on phosphate.

I'm fine if I don't have any detectable nitrate. Corals have simbiotic cyanobacteria, diazotrophs, that can provide nitrates. Corals much prefer the dissolved organic forms of nitrogen in amino acids and urea and the dissolved inorganic ammonia.

Fig. 3 from this paper Context Dependant Effects of Nutrient Loading on the Coral-Algal Mutualism

 

[KrisReef]

Over the decades I've seen a wide range of ratios in my systems. What I aim for is PO4 between .03 mg/l and .3 mg/l. For nitrate below 5 mg/l.

FWIW .03 mg/l is the threshold level to prevent phosphorus limitation in corals, identified by researchers at Southampton University in England using corals maintained in an aquarium for about a decade. .3mg/l is what corals are subjected to with upwelling in the ocean. .5 mg/l is acceptable as acros have been shown to incease growth up to this level. .9mg/l is the level teh Steinhart Aqaurium's ex situ sexually reproduced acro colonies are being grwon out with. Rich Ross's (who's part of the team at Steinhart) has his acro dominate mixed reef sitting at 1.8 mg/l, his tank can be seen at the beginning of his MACNA presentation on phosphate.

I'm fine if I don't have any detectable nitrate. Corals have simbiotic cyanobacteria, diazotrophs, that can provide nitrates. Corals much prefer the dissolved organic forms of nitrogen in amino acids and urea and the dissolved inorganic ammonia.

Fig. 3 from this paper Context Dependant Effects of Nutrient Loading on the Coral-Algal Mutualism

This is a very well thought out solution (with literature) to help explain how you came up with your numbers. Thank You. Extremely useful answer.

 

[Timfish]

This is a very well thought out solution (with literature) to help explain how you came up with your numbers. Thank You. Extremely useful answer.

I try! Thank you! I've gained a lot of insight over the decades and maybe one of the more humbling is the contradictions I've seen maintaining systems basicly the same way with same or similar animals and similar conditions. I do have to use anecdotal stuff sometimes but I prefer to back it up with what's been discovered by researchers, especiually when it offers answers or insight to the contradictions I've seen over the years.