Low Nitrates and high phosphate

CorbetJackson50

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Corals were telling me something was wrong so I tested everything. Nitrates were reading 0.9 ppm and Phosphate was .09 (I’m fine with this number).
In an effort to bring Nitrate up I have done a combination of things over the last week.
1. Small amounts of sodium nitrate added
2. Turned off refugium lights for 3 days. Then reduced photo period from 10 down to 8 hours.
3. Ramped up feeding

Fast forward 1 week and Nitrates is 4.2 and Phosphate .54 (not okay with this)

I have added GFO in a reactor. What else should I do to get this imbalance corrected?

Here is some additional tank info before others ask.
420g total volume
Reef Octopus 300 external recirc
Roller mat on one of 2 drains
Big Fuge approximately 60 gallons with chaeto.

Other parameters:
SG 1.026
Temp 76.6-77.5
PH 7.9-8.1
DKH 7.7
Calc 500
Mag ?

IMG_9469.jpeg IMG_9470.jpeg IMG_9534.jpeg
 

CHSUB

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I would go back to what you were doing before with respect to nutrients and look for another problem causing your coral’s issues. I have run tanks with both your listed inorganic nutrient levels with success. Imo, something else is causing coral problems.
 

rishma

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A couple of thoughts:

I find that additional feeding is helpful when phosphates are low. In my tank they tend to go up much faster with feeding than nitrate.

When I have low nitrate I find that dosing ammonia or nitrate is the best way to bring them up with minimal side effects ( though dosing ammonia tends to bring phosphates lower in my tank, it’s not a huge impact.)

If I were you I’d return the refugium lighting to how it was, dose nitrate, and run a very very very small amount of GFO to try snd slowly work back to a better nutrient levels.

And finally, I observe my coral are happy if nitrate is detectable. I aim for >5ppm, but thats just for a margin of error.
 
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CorbetJackson50

CorbetJackson50

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I would go back to what you were doing before with respect to nutrients and look for another problem causing your coral’s issues. I have run tanks with both your listed inorganic nutrient levels with success. Imo, something else is causing coral problems.
I’m convinced it’s the bottomed out nitrates. Historically this tank has not run low nitrates. I also run pretty high par. I believe the low nitrates paired with high par has caused the issues.
 
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CorbetJackson50

CorbetJackson50

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A couple of thoughts:

I find that additional feeding is helpful when phosphates are low. In my tank they tend to go up much faster with feeding than nitrate.

When I have low nitrate I find that dosing ammonia or nitrate is the best way to bring them up with minimal side effects ( though dosing ammonia tends to bring phosphates lower in my tank, it’s not a huge impact.)

If I were you I’d return the refugium lighting to how it was, dose nitrate, and run a very very very small amount of GFO to try snd slowly work back to a better nutrient levels.

And finally, I observe my coral are happy if nitrate is detectable. I aim for >5ppm, but thats just for a margin of error.
What do you recommend long term? I’d rather not have to dose nitrate or run gfo long term.

Should I run less chaeto, shorter photo period? Run skimmer less?

The only thing I can contribute to this reduction in nitrates is a recent swap of chaeto. Current strain of chaeto is growing better and much healthier looking than the previous.
 

rishma

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What do you recommend long term? I’d rather not have to dose nitrate or run gfo long term.

Should I run less chaeto, shorter photo period? Run skimmer less?

The only thing I can contribute to this reduction in nitrates is a recent swap of chaeto. Current strain of chaeto is growing better and much healthier looking than the previous.
Yes, you can tune your chaeto light photo period and intensity to better match your nutrient input. I’d do that after things are about back where you want them. I try to change one variable at a time. Whenever I change multiple variables it seems I end up chasing my tail.

The change you wanted to make was higher nitrate. Once you have nitrate and phosphate where you want them, try reducing both the nitrate dosing and chaeto lighting a little at a time to see if you can ween the tank off nitrate dosing. Keep an eye on phosphate while you do it. Hopefully it stays in the range you want. Finding the balance takes patience, in my experience, but it may be doable and I believe easier in a system with your volume.

Some tanks, like mine, are best managed with some nitrogen dosing. DIY dosing chemicals are cheap, so you may find that to be a good solution long term.
 

Randy Holmes-Farley

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In general, I don't think turning off refugium lights for 3 days is a good idea. Just reduce the photoperiod if you want less growth. You don't want the macroalgae in it to die. I'd stop the GFO and let phosphate move around on its own for a while. I'm also not sure if the phosphate rise isn't test error since i cannot see how it rose so much without nitrate rising significantly.
 

Ziggy17

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I just went through this. My hammers looks ***** but everything else looked great. Turns out My N was below 1 ppm. Coincidentally, around that time, I had a half dozen snails die off causing my P in get up to .35 ppm. I stopped carbon dosing and put 200g of Rowaphos in the bottom tray of the roller mat and removed the skimmer collection plug and let it drain back into the tank. It tool 2 weeks but my N is back up to 7 ppm and my P is back to (my normal) .08 ppm.
 

Ziggy17

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I should add that my tank is a RS 300XL, so with rocks and sand I’m at about 74g of total water volume. The death of a few snails can really jack my phosphate…. And that’s why I dosed 200g of rowaphos and not more. I didn’t want the P to swing back too quickly causing more issues.
 
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CorbetJackson50

CorbetJackson50

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Yes, you can tune your chaeto light photo period and intensity to better match your nutrient input. I’d do that after things are about back where you want them. I try to change one variable at a time. Whenever I change multiple variables it seems I end up chasing my tail.

The change you wanted to make was higher nitrate. Once you have nitrate and phosphate where you want them, try reducing both the nitrate dosing and chaeto lighting a little at a time to see if you can ween the tank off nitrate dosing. Keep an eye on phosphate while you do it. Hopefully it stays in the range you want. Finding the balance takes patience, in my experience, but it may be doable and I believe easier in a system with your volume.

Some tanks, like mine, are best managed with some nitrogen dosing. DIY dosing chemicals are cheap, so you may find that to be a good solution long term.
Fast forward a couple weeks and things aren’t any better. Actually worse. Nitrate .9 & Phosphate .9 no that’s not a typo and I’m sober .

Things I have done:
Skimmer has been off
Feeding heavy (50/50) frozen & pellets
No water changes
Running small amounts (1-2 cups) of GFO (maybe too small amounts for my 420g total volume)

Things I’m going to start doing now:
Dosing nitrate .5 ppm per day
Stopping with pellets and only feeding frozen.
Up the gfo?

What else should I do or not do.
 

Absolutekind

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I had the same problem for months. I put my skimmer on a timer for three hours a day and it raised nitrates to 7.0 consistently, and I did the same for my GFO reactor to raise phosphate to 0.06. I also put my ATS on a timer for six hours a day after the lights go off.

I feed once a day of homemade food.
 

Ziggy17

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What are you testing your No3 and PO4 with? Just doesn’t seem like your test results are accurate. Your N should increase more than it is with that Phos spike.

Unless you have a lot of GHA or another macro consuming the NO3.
 

rishma

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Fast forward a couple weeks and things aren’t any better. Actually worse. Nitrate .9 & Phosphate .9 no that’s not a typo and I’m sober .

Things I have done:
Skimmer has been off
Feeding heavy (50/50) frozen & pellets
No water changes
Running small amounts (1-2 cups) of GFO (maybe too small amounts for my 420g total volume)

Things I’m going to start doing now:
Dosing nitrate .5 ppm per day
Stopping with pellets and only feeding frozen.
Up the gfo?

What else should I do or not do.
Ok, I think the goal was higher nitrate.

Your previous parameters were good, but maybe not exactly what you wanted. I’d put things back how they were before your phosphate was high…and dose a nitrogen source.

I find that in my tank, more food quickly becomes more phosphate and often doesn’t impact nitrate, so your experience seems consistent with that. Whenever I want to raise nitrate, I have to dose a nitrogen source. Food never does it for me without a big increase in phosphate.

Running GFO definitely can help. If using a reactor, you can test the outlet of the reactor to know when it’s depleted.
 
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CorbetJackson50

CorbetJackson50

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What are you testing your No3 and PO4 with? Just doesn’t seem like your test results are accurate. Your N should increase more than it is with that Phos spike.

Unless you have a lot of GHA or another macro consuming the NO3.
Hanna checkers
They are not expired
Tests were done accurately and double checked.
I also didn’t believe it
 

Randy Holmes-Farley

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Things I’m going to start doing now:
Dosing nitrate .5 ppm per day
Stopping with pellets and only feeding frozen.
Up the gfo?

You might consider dosing ammonia instead of nitrate... but even if not that dose is low.

 

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