Which is worse: high nitrates or high phosphates?

IsaiahS609 · Feb 17, 2021

My nitrates are at 10 ppm but my phosphate has been at 0.1. Before I had euphyllia thriving in nitrate levels as high as 30 ppm but never tested for phosphate. Which is more dangerous to have elevated levels of?

Spare time · Feb 17, 2021

Phosphate will slow growth and cause algae issues. Nitrate can cause corals to become more susceptible to bleaching (I can't recall how much was in the study).

10ppm nitrate and 0.1 phosphate is not that high

jmichaelh7 · Feb 18, 2021

High phosphates = Algae issues period

IsaiahS609 · Feb 18, 2021

jmichaelh7 said:
High phosphates = Algae issues period

So high nitrates aren’t the main culprit of algae issues? It’s phosphate?

Daniel@R2R · Feb 18, 2021

Good discussion! My PO4 is currently at .08 and my nitrates are at 18 PPM. I'm working to bring both down still but was wondering if there's a balance factor I should watch out for and which one is worse to have elevated. I've always thought based on what I've read that phosphates are worse than nitrates.

KTTX · Feb 18, 2021

Daniel@R2R said:
Good discussion! My PO4 is currently at .08 and my nitrates are at 18 PPM. I'm working to bring both down still but was wondering if there's a balance factor I should watch out for and which one is worse to have elevated. I've always thought based on what I've read that phosphates are worse than nitrates.

Yea 16 to 1 usually

Potential · Feb 18, 2021

stop chasing numbers look at your corals sps can not take high nutrients buy lps and softies can know when corals look good and when they do not

derek.gray.988 · Feb 18, 2021

I've found that balance is important. High nitrates and no phosphates has led to cyano issues in tanks I've run. Elevated phosphates eventually seems to lead to hair algae issues.

jaxteller007 · Feb 18, 2021

My nitrates consistently run 20 to 40. Granted I have basically a FOWLR with only 3 small corals. But I until i dropped a big rock on my Duncan all my corals were thriving. And the fish definitely were.

EakTheFreak · Feb 18, 2021

I shoot for .05-.08 phosphates and 10 ppm Nitrates. I have LPS & softy tank. Even when nutrients go above these numbers things continue to look great. All the bad algae will grown in my refugium if levels get to high.

ThePurple12 · Feb 18, 2021

jmichaelh7 said:
High phosphates = Algae issues period

Please explain how you know this, and how do you define high phosphate? I got hair algae at 0 phosphate. Now it's at .1, and the GHA is going away.

Ross B Reef'n · Feb 18, 2021

Above everything I think balance/stability is the most important. These animals can survive just about anything in a stable environment. They die in situations where the tank owner obsesses over something. Every time you force parameters in a certain direction, you're fighting the tanks natural balance. This includes lighting. Small forced changes over long periods of time while letting nature play out is key.

Streetcred · Feb 18, 2021

Potential said:
stop chasing numbers look at your corals sps can not take high nutrients buy lps and softies can know when corals look good and when they do not

SPS will show reaction to an imbalance in the PO4:NO3 ratio very quickly losing color. LPS seems to be a lot more tolerant of imbalances in water chemistry.

Numbers need to be regarded in respect of maintaining balances in water chemistry ... ignore it at your peril.

Richyreefer · Feb 18, 2021

KTipp said:
Yea 16 to 1 usually

16 to 1 is n to p. 10 to 1 is NO3 to PO4. BRS has a great new series that really dives into this and explains it thoroughly.

Mhart032 · Feb 18, 2021

Phosphates are easier to bring down now days with LC and some media's. So I would say nitrates, it's really water change after water change after water change, the only real way I have found to bring them down. But really the cure is to find out why they are elivated.

Spare time · Feb 19, 2021

From what I can find in scholarly articles, corals can vary in their sensitivity to nitrate enrichment. Nitrate when combines with low phosphate or low available carbon, or with higher temperatures, or with low pH, can lead to issues with skeleton production and/or susceptibility to bleaching due to reduce tolerance, issues with zooxanthellae and chlorophyll increasing in numbers but then running out of phosphate and carbon, etc..

Phosphate seems toi increase tissue growth, but leads to brittle skeletons. The link below is on phosphate

I can add the other sources if anyone is interested, but I can't guarentee they can be accessed with out university info.

mdb_talon · Feb 19, 2021

Algae generally requires both nitrate and phosphate. I personally would prefer phosphates high because there is an easy rapid solution(gfo). There is not such an immediate solution to resolving high nitrates that i am aware of.

Keith Cuellar · Feb 19, 2021

Lol, I have nitrates as high as 60 and can keep most everything. Just started getting serious with algea control. Only a bit of hair algea on a piece of LR but my tang keeps it tamed. Honestly, I really couldn't be happier unless I "hybrid" my hydra 64s. HAPPY REEFING!