Struggling with 0 nitrates for a long time

CampAquarium · Dec 11, 2023

Our tank is about 1.5 years old, and is very well stocked. For the past couple of months, we have been wrestling with 0.0 nitrates. (Measured using the Hanna test) We tried to combat it by overfeeding, but then we had a spike in phosphates, and a subsequent GHA outbreak. We tried to combat it with NeoNitro, but saw our alk spike from 8.5 to 10.5, and we are still struggling to bring it down. We even swapped out our roller mat for filter socks to allow for more nutrients in the tank, and turned our skimmer down so that it's aerating the water but only filling its cup extremely slowly.

1. What gives?? What can/should we do?
2. Is it legit that the NeoNitro could have caused the alk spike? Or is it more likely that is a different, separate issue? In the past, dosing NeoNitro helped well with no adverse effects, but this time we saw absolutely no increase in nitrates and that spike in alk around the same time.
3. What actually "uses up" nitrates that would do so to this extent? Our tank was in a great, stable place with nitrates for over a year, only for it to drop like this with no discernible reason.

Our params:
Temp: 76.7
Salinity: 1.025
PH: 8.0
Alk: 9.5
Nitrates: 0.0
Phosphates: currently 0.03, had been up to 0.17 during their spike
Magnesium: 1465
Calcium: 386

Spare time · Dec 11, 2023

1. I prefer to dose amino acids. I think its less energetically costly to be used by corals and is a nitrogen source without phosphate.

2. https://www.reef2reef.com/threads/alkalinity-rising-from-dosing-nitrate.365780/

3. Zooxanthellae/Corals, other microbes, and algae.

jda · Dec 11, 2023

Is this a problem? Is your tank showing signs of any issues?

You don't need any nitrate to get nitrogen to you corals and other things. None. Your corals need nitrogen, not nitrate. Nitrate is a waste product and what is left over after a few other steps in ecosystem.

The only thing in any tank that needs nitrate is anaerobic bacteria, which is likely what is taking your nitrate to zero. These bacteria live in the sand and rocks where there is no oxygen and they are very good at turning no3 into N gas. This is the end of the nitrogen cycle - like the actual cycle and not what people call a cycle after some bottled bacteria and a X days of waiting.

If you are feeding well, then there is plenty of nitrogen in the ammonia or even nitrite, which are preferred ways to get nitrogen. Not all corals can do this, but those corals that can use nitrate have to covert it back to ammonia to be used - this costs extra energy in the 30-70% range which is expensive.

tritonpower · Dec 11, 2023

I have dosed neonitro for over 2 years to keep nitrate between 2.5-5. I dose it 3 times a week (2-3 caps usually for a 240 gallon system). I have never had an alk rise that I realized. I suspect if I did I simply turned my alk doser down a little. How are you dosing Alk?

CampAquarium · Dec 12, 2023

Spare time said:
1. I prefer to dose amino acids. I think its less energetically costly to be used by corals and is a nitrogen source without phosphate.

2. https://www.reef2reef.com/threads/alkalinity-rising-from-dosing-nitrate.365780/

3. Zooxanthellae/Corals, other microbes, and algae.

Thank you! I super appreciate how concise your reply is!

And I'll look into amino acid dosing for sure.

CampAquarium · Dec 12, 2023

jda said:
Is this a problem? Is your tank showing signs of any issues?

You don't need any nitrate to get nitrogen to you corals and other things. None. Your corals need nitrogen, not nitrate. Nitrate is a waste product and what is left over after a few other steps in ecosystem.

The only thing in any tank that needs nitrate is anaerobic bacteria, which is likely what is taking your nitrate to zero. These bacteria live in the sand and rocks where there is no oxygen and they are very good at turning no3 into N gas. This is the end of the nitrogen cycle - like the actual cycle and not what people call a cycle after some bottled bacteria and a X days of waiting.

If you are feeding well, then there is plenty of nitrogen in the ammonia or even nitrite, which are preferred ways to get nitrogen. Not all corals can do this, but those corals that can use nitrate have to covert it back to ammonia to be used - this costs extra energy in the 30-70% range which is expensive.

Our bubble tip anemone is looking sad, as well as one of our blue maxima clams. Overall our corals seem to have either stopped growing or are growing much more slowly that usual, and a few of them are totally retracted (GSP and a superman monti, to be exact).

We went over a year with nitrates in a solid place between 2-5, and then they just plummeted this fall and have NOT responded to any sort of activity to bring them up.

CampAquarium · Dec 12, 2023

tritonpower said:
I have dosed neonitro for over 2 years to keep nitrate between 2.5-5. I dose it 3 times a week (2-3 caps usually for a 240 gallon system). I have never had an alk rise that I realized. I suspect if I did I simply turned my alk doser down a little. How are you dosing Alk?

Yeah, we had dosed NeoNitro in the past with no issues. I'm going to try it again this week and keep a close eye on things/test alk and nitrates regularly. But we've had our alk dosing completely off for weeks now and are only barely seeing it decrease. I'm going to leave it off this week while I try the NeoNitro and see what happens.

Typically we dose Red Sea Foundation B via an automatic, daily timed dose from their Reefdose unit. I do water tests weekly to monitor levels and adjust the amount that is dosing. I test more often if we are in periods where a param is spiking, etc. Lately, the alk dose has been completely turned off. We are only dosing magnesium and calcium at the moment. The corals are absolutely blowing through the calcium. We've had to up our dose to 50 mL a day and it's barely keeping level!

jda · Dec 12, 2023

CampAquarium said:
We went over a year with nitrates in a solid place between 2-5, and then they just plummeted this fall and have NOT responded to any sort of activity to bring them up.

That is the anoxic bacteria population getting healthy. This is not bad. If you had a Hannah or sent a test out, you likely would have .1 to .3 no3 since the bacteria never seem to take them all the way to zero. If you are feeding well, then it is not a nitrogen thing since that nem cannot get nitrogen from nitrate anyway... I don't know about the clam, but it would have to convert it to ammonia if it did. I would look elsewhere like lighting.

When you add more nitrate sources, the bacteria multiply and consume them back down to near zero.

I know that the web, message boards and facebook and stuff seem to think that nitrate is some sort of coral food, but it is not. Nitrogen is a building block for new organic tissue and not a food or some form of energy. You just need a bit of nitrogen and everything in your tank except for likely anaerobic bacteria can use ammonia to get nitrogen.

I missed this the first time around, but when nitrate declines, alk rises. If you keep adding nitrate and then it gets used up, this can also cause a rise. If you leave the nitrate level alone (stop dosing nitrate), it will not rise. Somebody recently posted a formula in the chemistry forum, but I cannot find it offhand.

Spare time · Dec 12, 2023

jda said:
That is the anoxic bacteria population getting healthy. This is not bad. If you had a Hannah or sent a test out, you likely would have .1 to .3 no3 since the bacteria never seem to take them all the way to zero. If you are feeding well, then it is not a nitrogen thing since that nem cannot get nitrogen from nitrate anyway... I don't know about the clam, but it would have to convert it to ammonia if it did. I would look elsewhere like lighting.

When you add more nitrate sources, the bacteria multiply and consume them back down to near zero.

I know that the web, message boards and facebook and stuff seem to think that nitrate is some sort of coral food, but it is not. Nitrogen is a building block for new organic tissue and not a food or some form of energy. You just need a bit of nitrogen and everything in your tank except for likely anaerobic bacteria can use ammonia to get nitrogen.

I missed this the first time around, but when nitrate declines, alk rises. If you keep adding nitrate and then it gets used up, this can also cause a rise. If you leave the nitrate level alone (stop dosing nitrate), it will not rise. Somebody recently posted a formula in the chemistry forum, but I cannot find it offhand.

I am not sure why you seem to assume all corals do not use nitrate (at least that is why I am seeing). You can easily find papers of corals using nitrate.

jda · Dec 12, 2023

No you cannot. You can find papers that show that SOME hosts can convert nitrate back to ammonia for their symbionts, but also plenty of others that show that they cannot ever do it... ever. Corals is too broad of a word - most studies on coral mean true coral (stonies), by the way. There is plenty of research that show that anemones cannot use nitrate AT ALL. You won't find anything that shows that nitrate was used directly. You won't even find any good ones that show that nitrate was a preferred source of nitrogen... ammonia is prefered.

Besides, I try and specify that not all corals can use it. I should have never said ALL corals cannot use it and I certainly did not above - I was specific about two different organisms in the anemone and the clam. If I did then please point it out since I need to edit those posts.

Dburr1014 · Dec 12, 2023

OP, I know the feeling.
I stopped dosing and upped my feeding.
Nothing I can see really suffered.
My PO4 measures about 0.1 +/- 0.02 all the time.
As long as things look happy, I'm happy.