Nitrates High, Phosphates Low

Tempura and Teriyaki

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Hey. I am a newbie to this hobby, and I've had this 90 gallon tank for more than 2 months. The nitrates in the tank water is around 40ppm (saltwater), the water that I add to the tank is around 0ppm (freshwater). The phosphates in the tank water is around 0 ppm. I did not test the phosphates on the water that I add. Can someone more experienced tell me why the nitrates are high and the phosphates are low?

Also take into consideration.⬇️
(Two fish have disappeared in the last week or two. And I also fed fish twice yesterday.)
 
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vetteguy53081

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Keep it simple and safe. Nitrates will fluctuate in this time period. In the meantime, simple means adding a pouch of chemipure blue which will keep both nitrate and phosphate in check while polishing your water clarity
 

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I have no real proof but I had low po4 and high no3. I was running a refugium and gfo - could not get no3 down. I let my gfo get exhausted and noticed po4 rise a little. Once I let po4 rise my no3 started decreasing? So I started running less gfo, and po4 went up to .4 and no3 came from 50ppm to 20ppm.

I have no idea why? Maybe coincidence? But figured I would share- maybe there is some value in my experience.
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Assuming the tank is started "clean" with dead rock, it is unlikely there is any phosphate. As you add food (depending on the food type) you are adding ammonia and phosphates. The ammonia gets converted to nitrites then nitrates and for the most part remains in the water. Phosphates in the beginning will get bound up into rock/sand (aragonite). This will continue to happen until it reaches a level of saturation. At the point it will begin leaching back into the water and be available for testing as a residual.

Water changes will remove nitrate, but very little PO4.

Contrary to many articles published before say, 2014 or so, you need to always have some PO4 and NO3 present to support coral growth.
 

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I have no real proof but I had low po4 and high no3. I was running a refugium and gfo - could not get no3 down. I let my gfo get exhausted and noticed po4 rise a little. Once I let po4 rise my no3 started decreasing? So I started running less gfo, and po4 went up to .4 and no3 came from 50ppm to 20ppm.

I have no idea why? Maybe coincidence? But figured I would share- maybe there is some value in my experience.
CB392F4E-3F5D-45F7-8627-7E8BCE360FDB.jpeg
Yes, this is a thing absolutely. The reverse is also true. The bacteria that process both nutrients can be limited by a shortage of one or the other.
 

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In my system I had low phos .02-.04 and high nitrates40-80. My nitrates would continue to climb after many forms of eradication. Not until I started dosing phosphates did I noticed that, nitrate needs phosphates to be consumed.
 

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Tempura and Teriyaki

Tempura and Teriyaki

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When things die you can get a twmporary ammonia - nitrite - nitrate increase. What are you running for filtration? (skimmers, reactors, biological media, etc.) How much rock do you have in your tank, sump, etc.?
there is skimmer and bio balls and chemipure for filtration. There are a few small rocks in sump. Rocks in tank have been stacked up. This is a preexisting tank that has been moved and the rock is alive. I have no gfo.
 

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there is skimmer and bio balls and chemipure for filtration. There are a few small rocks in sump. Rocks in tank have been stacked up. This is a preexisting tank that has been moved and the rock is alive. I have no gfo.
Are you using filter floss? Also, how often are you cleaning your bio balls? (if left uncleaned they can lead to high nitrates) Chemipure is more for clearing the water and removing phosphates. Ideally you want something like sock filters or filter floss that you can either discard or change out every few days to a week (this will actually remove the vast majority of your nitrates).
 
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there is skimmer and bio balls and chemipure for filtration. There are a few small rocks in sump. Rocks in tank have been stacked up. This is a preexisting tank that has been moved and the rock is alive. I have no gfo.
Chemipure Blue is just activated carbon. Chemipure Elite is carbon AND GFO which removes PO4. Neither effects NO3 to much degree. Switch to Blue to let a little PO4 show up. You don't need much, but >0 is better. Again with the caveat: if you are feeding 3+ times per day then low nutrient residuals are much less of a concern.
 

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Hey. I am a newbie to this hobby, and I've had this 90 gallon tank for more than 2 months. The nitrates in the tank water is around 40ppm (saltwater), the water that I add to the tank is around 0ppm (freshwater). The phosphates in the tank water is around 0 ppm. I did not test the phosphates on the water that I add. Can someone more experienced tell me why the nitrates are high and the phosphates are low?

Also take into consideration.⬇️
(Two fish have disappeared in the last week or two. And I also fed fish twice yesterday.)
Hey I just noticed you joined today! We need to get the welcome party going for this new member everyone. Wish I could tag everybody with a hospitality badge right now
 
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Tempura and Teriyaki

Tempura and Teriyaki

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Are you using filter floss? Also, how often are you cleaning your bio balls? (if left uncleaned they can lead to high nitrates) Chemipure is more for clearing the water and removing phosphates. Ideally you want something like sock filters or filter floss that you can either discard or change out every few days to a week (this will actually remove the vast majority of your nitrates).
I do not have filter floss. I’m not sure if they are bio balls. It like rocks and they are shaped In circles and squares. Sock filters or filter floss seems like a good idea.

scottb, thank you for the chemipure info. :D
 
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blaxsun

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I do not have filter floss. I’m not sure if they are bio balls. It like rocks and they are shaped In circles and squares. Sock filters or filter floss seems like a good idea.

scottb, thank you for the chemipure info. :D
What kind of tank do you have? (Innovative Marine, etc.) Could you share a picture of your sump or where your filtration is? ie: where the water leaves the tank, is filtered and then returned.

I think I may know what is contributing to your problem. The cubes and spheres you’re referring to are probably MarinePure bio cubes and spheres - but they’re not the issue (they’re lightweight ceramic and can crumble easily?) But i’ll need to see a picture of your sump, return pump, etc.
 
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Tempura and Teriyaki

Tempura and Teriyaki

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What kind of tank do you have? (Innovative Marine, etc.) Could you share a picture of your sump or where your filtration is? ie: where the water leaves the tank, is filtered and then returned.

I think I may know what is contributing to your problem. The cubes and spheres you’re referring to are probably MarinePure bio cubes and spheres - but they’re not the issue (they’re lightweight ceramic and can crumble easily?) But i’ll need to see a picture of your sump, return pump, etc.
i took another nitrate test today, and I took it from the tank instead of the sump. I think the marinepure bio cubes and spheres are the problem. In the Tank, the nitrate level is around 20 ppm and in the sump, it is 40 ppm.

the tank is all glass, and the sump is eshopps.
 

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blaxsun

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Is that the heater in the middle chamber? I can’t tell what you have in the right chamber, but it looks like the skimmer and return pump in the left? The first thing I see is that you don’t appear to have any filtration - other than the skimmer. Usually your overflow drains into a chamber where it runs through one or more sock filters.

The bio blocks and rock may be your only saving grace at this point, so removing them might spike your nitrates. You could rinse them out in some tank water (not tap water) to preserve most of the beneficial bacteria.
 

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Middle chamber heater, right side is return pump. Left side skimmer.

how come the nitrates down there are high, but in the tank, they are at 20 ppm?
Well, you need some kind of filtration in the left chamber - filter socks would be a good addition. This is where you can also run carbon and GFO in a media basket.

I would move the skimmer to the middle with the bio rocks (after you thoroughly rinse them), as the unfiltered water is probably clogging them up a bit. You could also place the rocks on the left under/after the filter socks. You may find that your skimmer runs better as well (or needs less emptying). Heater in the middle chamber is fine.

You’re also missing the black sponge that fits in the gap between the middle and right chamber (not a big deal).

I honestly can’t offer an explanation for the nitrates discrepancy, other than you may have more in the sump because the bio balls are having some benefit. I think if you make a few changes with the sock filters, rinse the rocks and clean the sump - you might see some benefit.
 
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