High nitrates

[TerrellC]

At my last testing nitrates were 42.7 and phosphates at 0.09. I've tried water changes, refugium, and reducing feeding. Tank is 1.5 years old, mixed Reef. My N/P ratio is too high to use Elimi NP. Any ideas?

 

[bluemon]

At my last testing nitrates were 42.7 and phosphates at 0.09. I've tried water changes, refugium, and reducing feeding. Tank is 1.5 years old, mixed Reef. My N/P ratio is too high to use Elimi NP. Any ideas?

Elimini NP is just a carbon source so honestly whatever ratio should eat away at the carbon.

I don’t believe in this magical NP ratio people talk about

I would just use vinegar or vodka dosing myself.

Also, you might have some detritus/nitrate factory somewhere if WC does not reduce nitrates. A 50% WC should reduce nitrates by 50% as unlike phosphates, nitrate is not absorbed by rocks.

Do you have things like bioballs or maybe layers of detritus in the overflow or sump?

Besides all that , your nitrate isn’t that higher either.

 

[gbroadbridge]

At my last testing nitrates were 42.7 and phosphates at 0.09. I've tried water changes, refugium, and reducing feeding. Tank is 1.5 years old, mixed Reef. My N/P ratio is too high to use Elimi NP. Any ideas?

40ppm Nitrate is not particularly high.

If you do a 20% water change you will drop the Nitrate by 20%, a 50% WC will drop them by 50%.

Carbon dosing does work, it just takes while (up to a couple of months) to start working.
I dose White Vinegar rather than some expensive proprietary potion.

 

[BryanM]

At my last testing nitrates were 42.7 and phosphates at 0.09. I've tried water changes, refugium, and reducing feeding. Tank is 1.5 years old, mixed Reef. My N/P ratio is too high to use Elimi NP. Any ideas?

water changes is probably the best and easiest way to lower your nitrates. What's more interesting is what happens a few days after the water change, do they creep back up?

I'm not a fan of reduced feeding unless you were actually over feeding.

I've never focused on "the ratio" myself.

 

[Randy Holmes-Farley Verified Community Expert]

The current values are within my target range.

What size tank are we talking about?

 

[TerrellC]

You're OK with nitrates in the 40's? I've got a 90 display with a 20 gallon sump- Waterbox 110.4.

 

[Randy Holmes-Farley Verified Community Expert]

You're OK with nitrates in the 40's? I've got a 90 display with a 20 gallon sump- Waterbox 110.4.

Yes. The rationale and tank examples are here:

https://www.reef2reef.com/ams/randy’s-thoughts-on-nutrient-target-ranges.1087/
4. What targets seem reasonable? Of course, that depends on all the other factors at play, such as types of corals, availability of ammonia, particulate foods, etc. However, for a mature mixed reef, this would be how I personally would run it:

• Let nitrate float between 5 ppm and 50 ppm. I’d use gentle export in this range, such as growing macroalgae.
• Above 50 ppm, I’d begin to focus more on reducing it, by organic carbon dosing, turf or macroalgae, etc.
• Below 5 ppm, I’d begin to dose ammonia or feed more. The target level might drop lower if dosing ammonia, just like the heavy in/heavy out scenario where nitrate may not be as needed.
• Let phosphate float between about 0.06 ppm and 0.3 ppm. This range is higher than I’ve recommended in the past. I’d use gentle export in this range, such as growing macroalgae.
• Above about 0.3 ppm, I’d begin to focus more on reducing it, by turf or macroalgae, or a binder such as GFO or lanthanum (has its own risks to tangs). If a binder: GO SLOW. Turf and macroalgae will typically be slow enough.
• Below 0.06 ppm, I’d begin to dose sodium phosphate or feed more to get the level up.

 

[TerrellC]

Given the idea of more relaxed ranges I'd still like to get my nitrates down. Would it be appropriate to start carbon dosing with eg. NP Bacto Balance?

 

[gbroadbridge]

Given the idea of more relaxed ranges I'd still like to get my nitrates down. Would it be appropriate to start carbon dosing with eg. NP Bacto Balance?

Vinegar is a lot cheaper and has the same effect.

Given your current level I would test weekly and if you see an increase over time some form of carbon dosing may we worthwhile.

 

[bluemon]

Vinegar is a lot cheaper and has the same effect.

I do a 50/50 mix of 30% vinegar and vodka myself.

Offsets the pH drop a bit.

Super cheap as well

 

[JonasRoman]

Yes. The rationale and tank examples are here:

https://www.reef2reef.com/ams/randy’s-thoughts-on-nutrient-target-ranges.1087/
4. What targets seem reasonable? Of course, that depends on all the other factors at play, such as types of corals, availability of ammonia, particulate foods, etc. However, for a mature mixed reef, this would be how I personally would run it:

• Let nitrate float between 5 ppm and 50 ppm. I’d use gentle export in this range, such as growing macroalgae.
• Above 50 ppm, I’d begin to focus more on reducing it, by organic carbon dosing, turf or macroalgae, etc.
• Below 5 ppm, I’d begin to dose ammonia or feed more. The target level might drop lower if dosing ammonia, just like the heavy in/heavy out scenario where nitrate may not be as needed.
• Let phosphate float between about 0.06 ppm and 0.3 ppm. This range is higher than I’ve recommended in the past. I’d use gentle export in this range, such as growing macroalgae.
• Above about 0.3 ppm, I’d begin to focus more on reducing it, by turf or macroalgae, or a binder such as GFO or lanthanum (has its own risks to tangs). If a binder: GO SLOW. Turf and macroalgae will typically be slow enough.
• Below 0.06 ppm, I’d begin to dose sodium phosphate or feed more to get the level up.

Very relaxed and interesting input. Even if i not sure I have same goals its interesting we can find tanks that thrive in both extremes.
I would though hesitate to make too many conclusions based on "this tank has sky high NP and still looks good " . I know you don't but someone can misunderstand the message and extrapolate such conclusions. Because you could also say "despite these unnatural high NP values the tank looks good thanks to compensation mechanism"
If that's the case the pedagogy is not to relax but just see this as an evidence that corals are masters of adaptation.
Isn't it better to run safe and keep NP more close to nature? Also, to really make conclusions on singular case says nothing but we should need a database with correlation data between NP and how tank looks. If we had that I am not so sure the majority of pics looks that healthy like in your examples.
All of us that have been in this hobby for a while I think agree that we have seen more tank that's are healthy that has normal NP than the opposite. So with this said, your examples tells us that corals may adapt to unnatural conditions. But if you introduce a new coral to that system, I wonder how that goes?

 

[JonasRoman]

At my last testing nitrates were 42.7 and phosphates at 0.09. I've tried water changes, refugium, and reducing feeding. Tank is 1.5 years old, mixed Reef. My N/P ratio is too high to use Elimi NP. Any ideas?

May I ask how you measure nitrate and what is the value of nitrit?

 

[JonasRoman]

At my last testing nitrates were 42.7 and phosphates at 0.09. I've tried water changes, refugium, and reducing feeding. Tank is 1.5 years old, mixed Reef. My N/P ratio is too high to use Elimi NP. Any ideas?

If your values are confirmed I would not dose carbon as your P is too low for that. Not correct ratio. P will be zero quickly and that's not good.

You need a method that selectively reduce nitrate and that's denitrifation. Thus either a nitrate reactor or try with maxspects anaerob blocks with a local containing carbon source. It takes 4 weeks before they start to work. Maybe introduce 2-3 to start with.

Jonas

 

[gbroadbridge]

If your values are confirmed I would not dose carbon as your P is too low for that. Not correct ratio. P will be zero quickly and that's not good.

You need a method that selectively reduce nitrate and that's denitrifation. Thus either a nitrate reactor or try with maxspects anaerob blocks with a local containing carbon source. It takes 4 weeks before they start to work. Maybe introduce 2-3 to start with.

Jonas

You say don't dose carbon and then suggest using a carbon source in the next paragraph?

 

[EnterName]

You're OK with nitrates in the 40's? I've got a 90 display with a 20 gallon sump- Waterbox 110.4.

Yes. The rationale and tank examples are here:

https://www.reef2reef.com/ams/randy’s-thoughts-on-nutrient-target-ranges.1087/
4. What targets seem reasonable? Of course, that depends on all the other factors at play, such as types of corals, availability of ammonia, particulate foods, etc. However, for a mature mixed reef, this would be how I personally would run it:

• Let nitrate float between 5 ppm and 50 ppm. I’d use gentle export in this range, such as growing macroalgae.
• Above 50 ppm, I’d begin to focus more on reducing it, by organic carbon dosing, turf or macroalgae, etc.
• Below 5 ppm, I’d begin to dose ammonia or feed more. The target level might drop lower if dosing ammonia, just like the heavy in/heavy out scenario where nitrate may not be as needed.
• Let phosphate float between about 0.06 ppm and 0.3 ppm. This range is higher than I’ve recommended in the past. I’d use gentle export in this range, such as growing macroalgae.
• Above about 0.3 ppm, I’d begin to focus more on reducing it, by turf or macroalgae, or a binder such as GFO or lanthanum (has its own risks to tangs). If a binder: GO SLOW. Turf and macroalgae will typically be slow enough.
• Below 0.06 ppm, I’d begin to dose sodium phosphate or feed more to get the level up.

As usual great article!

I was wondering if concentrations like 50-100ppm NO3 are really safe for fish (long term). Sure, LC50 values for 48h exposure are ridiculously high (see citations: https://www.researchgate.net/publication/229537466_Nitrate_Toxicity_to_Five_Species_of_Marine_Fish), but people want to keep fish healthy over years.

I found a study that summarizes their findings by recommending to keep NO3-N below 20mg/L for marine fish (≈ 89mg/l NO3 if my math isn't totally off). But they also said some species might be already affected at half the concentration if they are adapted to low nutrient environments. (https://www.sciencedirect.com/science/article/abs/pii/S0045653504009993).

Did you manage to come across some good studies on this topic throughout your research? I would really love to learn more about it!

 

[Randy Holmes-Farley Verified Community Expert]

Given the idea of more relaxed ranges I'd still like to get my nitrates down. Would it be appropriate to start carbon dosing with eg. NP Bacto Balance?

I’d personally use vinegar, but yes, carbon dosing is a fine plan, and watch phosphate to make sure it does not decline too much.

 

[Randy Holmes-Farley Verified Community Expert]

As usual great article!

I was wondering if concentrations like 50-100ppm NO3 are really safe for fish (long term). Sure, LC50 values for 48h exposure are ridiculously high (see citations: https://www.researchgate.net/publication/229537466_Nitrate_Toxicity_to_Five_Species_of_Marine_Fish), but people want to keep fish healthy over years.

I found a study that summarizes their findings by recommending to keep NO3-N below 20mg/L for marine fish (≈ 89mg/l NO3 if my math isn't totally off). But they also said some species might be already affected at half the concentration if they are adapted to low nutrient environments. (https://www.sciencedirect.com/science/article/abs/pii/S0045653504009993).

Did you manage to come across some good studies on this topic throughout your research? I would really love to learn more about it!

I did not look for science studies, I just looked at reef tank examples.

 

[TerrellC]

At my last testing nitrates were 42.7 and phosphates at 0.09. I've tried water changes, refugium, and reducing feeding. Tank is 1.5 years old, mixed Reef. My N/P ratio is too high to use Elimi NP. Any ideas?

May I ask how you measure nitrate and what is the value of nitrit?

Hanna checkers for both. Nitrite = 14.