High Nitrate - Low Phosphate

[clowns]

Good afternoon,

First off, I am only leaving this here as a place for new and intermediate reefers to find some information. I by no means claim to be an expert but am only providing this "trial, error and success" steps that I took to solve a major problem that I do not see discussed very much, nor covered in many articles. Largely information I had to piece together and risk testing on my own. This is largely because it doesn't seem to be a very common problem. Seeing as I almost quit the hobby myself over it, I know that there is someone else out there struggling with the same problem and/or wanting to shut their system down.

The problem:
High Nitrates and Low Phosphates. By high nitrates I mean constantly rising, off the charts nitrates with phosphates at or "near-zero". Something like 100ppm NO3 and 0.02 phosphate.

The symptoms:
Nitrates will not come down. Phosphate will not go up. You have a good skimmer thats not pulling much, youve maybetried carbon dosing, a refugium or a denitrator, you're doing large water changes (50%+) multiple times a week but the nitrate just shoots back up within a day. You've cleaned everything you can, have no visible dead spots. Zero to very small amounts of Algae Growth. Water looks clean. Corals seem to be okay but don't thrive, some die fairly quick. SPS dies at an almost 100% rate.

The cause:
In short, it could be a lack of phosphate. For me it was GFO stripping all/most PO4. But for others it could be something else that disproportionately removes more PO4 that NO3.

Things to take into consideration:
Redfield Ratio. There is a lot of information here so I urge you to look into it if you are having this problem. The basics of it are as such: 106 Carbon to 16 Nitrogen (Nitrate) to 1 Phosphate. Now there is a lot of discussion surrounding Redfield Ratio and the importance of aiming for it, however it does illustrate that organisms in the home aquaria that dispose of Nitrate do require phosphate and carbon in order to do so. If you are at 100ppm NO3 and 0.02 PO4, you are at a NO3 to PO4 ratio of 5000:1. This will undoubtably hinder NO3 reduction.

The solution:
- Disable all phosphate removal media and go back to basics. Absolutely no GFO.

- Use the redfield ratio as a loose guideline and SLOWLY rebalancing the system through phosphate dosing. Depending on how out of whack your system is, you can do this from simply feeding more "high-phosphate" foods or dosing something like Brightwell's NeoPhos. I chose NeoPhos as I didn't want decomposing extra food to exacerbate the nitrate problem since I was over 100ppm Nitrate already.

- Test Phosphates daily. I recommend getting a Hanna ULR Phosphorous Checker to save you time. Pay attention to what youre bottoming out at. For me, my readings consistently came back 0.02. Most advice will tell you this is a great number to be at, however due to the steadfastness of this number, I believe that my results were actually zero. These tests can have a margin of error.

- Dose Safe Amounts of Phosphate Daily. if you are seeing a consistent zero or near zero measurement, dose a small amount of phosphate that, per instructions, should bring you up to say .04 total ppm. Test the following day and see where you are at. If you are back down to your zero/near zero levels, this is a "good sign". Something is consuming your phosphate. Something needed it. Do that for a week and if you keep coming back to zero daily, up the dose to bring you to .08 and test daily again. Your phosphate could be going one of a few places: Absorbed by rock, consumed by bacteria or consumed by algae. You may start seeing small, decreases in your nitrates at this point. If ever you test and the level hasn't come down to your original zero/near zero reading do not dose. You do not want to over do it because it can have negative side effects on your living organisms in high amounts.

- Pay attention to the algae/cyano. If ever a meaningful amount algae begins to pop up, stop dosing phosphate and see what happens to the algae. If it grows, there is still phosphate in the water, if it dies that means that there isnt. Essentially treat the algae like a visual representation of the denitrifying bacteria who are also vying for the same PO4 and NO3.

My end experience:
When I first dosed PO4, my tank was absorbing it at an absurd rate (.08 gone in 2 hours) and I had no algae. This gradually slowed down over time (.08 in 2 days) with small amounts of Cyano. My nitrate dropped from 100+ to a consistent 50 at about the 2 month mark with medium amounts of Cyano after each dose. At this point dosing once every 2-3 days. This tanked to 10ppm about a month later with a huge cyano outbreak after one of the doses. I siphoned this out as it signified the end of the need to dose as the PO4 was being mostly absorbed by algae. My phosphates still remain in the .04 range with Nitrate at 5.

Again, this I am not an expert nor claim to be. Just sharing my experience in hopes that it might help someone like me who was really struggling for a very long time with this issue. If it helps 1 person, I'm glad I took the time to post. Please call me out if something is wrong or you have any questions.

Happy reefing and happy new year

Thank you!!! Mine aren't that far out of line but can't keep any phosphates..

 

[clowns]

Thank you!!! Mine aren't that far out of line but can't keep any phosphates..

I am wanting to start a small hob refugium for macro and copepods, for future mandarin...
With my nitrates about 30 and no phosphates, any ideas about starting refugium...

 

[Randy Holmes-Farley]

I am wanting to start a small hob refugium for macro and copepods, for future mandarin...
With my nitrates about 30 and no phosphates, any ideas about starting refugium...

Dose food grade sodium phosphate.

 

[GunnarH]

Thank you for posting this!

I'm about five days into dosing the recommended amount of NeoPhos. It is gone in minutes. So fast, I started doubting my Hanna ULR Phosphate checker. I ordered new reagent as well as the calibration check set. Turns out my Hanna device is correct. Or, at least within spec.

The Brightwell Aquatics instructions for NeoPhos state (quote): "If concentrations remain unchanged, then the system is likely carbon-limited. Dose with REEF BIOFUEL"

Any thoughts on this?

 

[Comic_Reef]

Thank you for posting this!

I'm about five days into dosing the recommended amount of NeoPhos. It is gone in minutes. So fast, I started doubting my Hanna ULR Phosphate checker. I ordered new reagent as well as the calibration check set. Turns out my Hanna device is correct. Or, at least within spec.

The Brightwell Aquatics instructions for NeoPhos state (quote): "If concentrations remain unchanged, then the system is likely carbon-limited. Dose with REEF BIOFUEL"

Any thoughts on this?

I've never used BioFuel before but from what I understand, that is a Carbon Dosing replacement which may make a low nutrient issue worse. Typically you carbon dose to lower nutrients.

If you're having trouble keeping phosphates in the system and that's leading to negative results, I would just stick to dosing phosphates or feeding more (if your nitrates aren't high)

For years I battled low phosphates and aimed to stay in that 0.03-0.05 range but that just always seemed to leave me in a position where a missed dose or slight increase in consumption would just bottom them out and lead to die off. I listen a lot to the anecdotal evidence I hear from a lot of vendors who like to keep their phosphates in the 0.1-0.15 range. Since shifting to that way of thinking, I haven't had many issues keeping coral alive assuming alkalinity stayed stable.

 

[GunnarH]

(if your nitrates aren't high)

Sorry, I forgot to mention. Yes, my nitrates are high, around 83 according to an ICP (tank water was sampled three weeks ago). My Hanna checker blinks 75.0 and hasn’t budged in weeks.

My phosphates were 0.027 according to that same ICP, 0.00 or 0.01 according to my Hanna ULR checker.

But your point is well taken, I’ll keep going with the NeoPhos for now. Thanks!

 

[GunnarH]

I'm a little unsure how to proceed now.

Yesterday and today my Hanna Phosphates ULR checker has reported 0.02. This is up from a steady 0.00 (occasionally 0.01) since March 1.

Nitrates are still above 75 (Hanna HR blinking 75.0).

Do I dose more NeoPhos today, or do I wait and see if it has stabilized?

If I do dose today, should I dose the amount to raise my phosphates by 0.01, 0.02, or 0.04? Before yesterday I had been dosing to raise it by 0.04 for a few days. Before that, I dosed to raise by 0.01, then 0.02, but neither seemed to do much. It was always back to 0.00 within hours.

I don't want my phosphates to spike, but also not to flatline again. I'd love some advice from those who've been here before.

Thanks!

 

[Randy Holmes-Farley]

Yes, I’d dose more.

 

[dor_L]

Hello and thank you for sharing this important information. For me, it also solved the problem that my corals did not open like GSP because the phosphate was at zero for a long time. Do you suggest adding phosphate without carbon dosing until the system stops absorbing the phosphate and it stabilizes?

 

[GunnarH]

Progress report: I've now measured phosphates at around 0.05 (± 0.01) for almost two weeks. Nitrates are still stuck at my Hanna checker blinking 75.0.

On a more positive note, my hammers are opening up again, although my torches are still struggling. No cyano outbreak, but I still have that reddish-brown dust on the glass and sand during the photoperiod. That's easy enough to remove, though.

My question now is: should I try to keep the phosphates around 0.05, or would it be better to try to slowly increase it to around 0.08 - 0.1? And how long should I expect it to take for the nitrates to start dropping below 75?

 

[alex37310]

Progress report: I've now measured phosphates at around 0.05 (± 0.01) for almost two weeks. Nitrates are still stuck at my Hanna checker blinking 75.0.

On a more positive note, my hammers are opening up again, although my torches are still struggling. No cyano outbreak, but I still have that reddish-brown dust on the glass and sand during the photoperiod. That's easy enough to remove, though.

My question now is: should I try to keep the phosphates around 0.05, or would it be better to try to slowly increase it to around 0.08 - 0.1? And how long should I expect it to take for the nitrates to start dropping below 75?

Any update on your issues?

 

[GunnarH]

update

Yes: my nitrates are finally down. In fact, they have bottomed out. I did three things:

1. Reduced feeding. I've since gone back to my original feeding schedule since the nitrates bottomed out.
2. Added a Tunze submersible LED stick and a powerhead to my refugium, and started growing chaeto by the pound.
3. Dosed carbon (I use Brightwell Reef BioFuel).
4. Kept dosing phosphates (I use Brightwell NeoPhos).

No connection to Brightwell.

It took a while, but the nitrates have come down, while the phosphates have held at 0.02 or so. Now I have a severe attack of green hairy algae, but that's a different story.

 

[Randy Holmes-Farley]

It took a while, but the nitrates have come down, while the phosphates have held at 0.02 or so. Now I have a severe attack of green hairy algae, but that's a different story.

All other things aside, that points out that trying to deal with algae by reducing nutrients is often not a good way to go.

 

[GunnarH]

trying to deal with algae by reducing nutrients is often not a good way

That's how it looks to me, yes.

My GHA are finally under control, and the thing that worked for me was greatly reduced lighting for a prolonged period of time (months). I'm running two Kessil AP9X at 15% intensity for one hour each day, with one hour ramps on either side. IOW, a photoperiod of three hours, with only one hour at the max of 15%. There is ambient daylight in the room, but no direct sunlight hitting the tank and low lighting for the humans at night.

Obviously, this is not a good solution if you have lots of expensive corals that demand a lot of light. I did not. Unsurprisingly, the corals that survived the GHA onslaught have had no problems surviving the reduced lighting. Even my Rose Bubble Tip Anemones have survived.

Before I decided to try this, I'd tried pretty much everything else: Ripping out the GHA by hand once a week. Cutting the light completely and wrapping the tank first for three days, then for 5 days. Reducing feeding to the absolute minimum. Nothing worked. The GHA bounced back immediately.

Current status is that my nutrients are holding at near zero, my chaeto is growing well (I doubled the light in the refugium when I reduced the lighting in the display), and the green hairy stuff is almost gone.

I'll try slowly increasing the photoperiod again once I'm convinced the GHA is completely gone. This is one battle I do not wish to repeat.