Low Phosphate but High Nitrate?

[JIsBusyReefing]

Hi everyone. I'm having an issue with my nutrient levels and am looking for some feedback, as this issue seems to be rare. I setup a 150g tank back in July and it cycled through just fine. I started adding corals and fish over the course of 4 months til recently and every time I test the water, I have little to no phosphate and very high nitrate running from 40 to 80ppm. When I started noticing this issue, I took advice from others to reduce feeding, get some macro algae, do water changes, and vacuum the sand bed. I've done that for weeks but it has not fixed the issue.

Chronically, I have rust colored looking dust material that grows on the sand bed everywhere where there is light. Some have told me it's just diatoms while others tell me it's cyano. I have no idea what to think about it. But it takes over the bed in a few days after vacuuming it up. Just comes right back and never goes away. I've never had any macro algae blooms in the tank. Just coralline. Hazey film builds on the glass within a few days also and I do have some calcified green algae on the glass too. I haven't had any corals die (though some don't look exactly happy all the time) but I have a heck of a time keeping BTAs, as they die within a couple of weeks anytime I add one. On the other hand, I have a giant Ritteri that has done great in the tank for the past 3 months. No issues.

Here's what I got running for filtration
-x3 filter socks
-reef octopus classic 150INT skimmer
-refugium lit 12hrs/day w/ caulerpa

I was thinking about adding a biopellet reactor but I'm not sure now with this going on. Any ideas?

 

[Jonify]

Hi everyone. I'm having an issue with my nutrient levels and am looking for some feedback, as this issue seems to be rare. I setup a 150g tank back in July and it cycled through just fine. I started adding corals and fish over the course of 4 months til recently and every time I test the water, I have little to no phosphate and very high nitrate running from 40 to 80ppm. When I started noticing this issue, I took advice from others to reduce feeding, get some macro algae, do water changes, and vacuum the sand bed. I've done that for weeks but it has not fixed the issue.

Chronically, I have rust colored looking dust material that grows on the sand bed everywhere where there is light. Some have told me it's just diatoms while others tell me it's cyano. I have no idea what to think about it. But it takes over the bed in a few days after vacuuming it up. Just comes right back and never goes away. I've never had any macro algae blooms in the tank. Just coralline. Hazey film builds on the glass within a few days also and I do have some calcified green algae on the glass too. I haven't had any corals die (though some don't look exactly happy all the time) but I have a heck of a time keeping BTAs, as they die within a couple of weeks anytime I add one. On the other hand, I have a giant Ritteri that has done great in the tank for the past 3 months. No issues.

Here's what I got running for filtration
-x3 filter socks
-reef octopus classic 150INT skimmer
-refugium lit 12hrs/day w/ caulerpa

I was thinking about adding a biopellet reactor but I'm not sure now with this going on. Any ideas?

When you say water changes, how much and how frequently? 40-80 is pretty high. What is the actual level of phosphates in your tank?

 

[JIsBusyReefing]

When you say water changes, how much and how frequently? 40-80 is pretty high. What is the actual level of phosphates in your tank?

I did 20% water changes once a week while reducing feeding to once a day in the morning and only just enough that everyone gets something. Didn't make a difference, so I tried reducing the frequency of water changes to try and bring phosphate up. Also made no difference. My parameters remain consistent whether I do a water changes or not. My LFS has also tested my water on a whim that my test kit is faulty. They show the same levels.

I'm not sure on the exact level of phosphate because I'm using API. But it always shows 0ppm.

 

[Jonify]

Alright, two things: first, grab an ultra low phosphate Hanna checker to confirm. If your phosphate is truly bottomed out, that will impact your nitrates--without phosphates, the nitrate will generally stay where it is, since most organisms need to consume both in a fairly balanced proportion. So if your phosphates are 0, your nitrate level will stop falling. Try bumping up your phosphates to 0.02 - .1 with extra feeding, or with something like Brightwell NeoPhos. Once you get your phosphates up, your nitrates will start to fall again. (But first, check your actual phosphate level with the Hanna ULR checker to verify it has actually bottomed out).

Second, if your phosphates aren't actually bottomed out, you can keep doing what you're doing, but increase either the frequency of water changes, or the volume. You could go up to something like 50% a week. 20% a week is only going to drop you from 40-80 to 30-64, which is still too high, and by the time you do your next water change, it's already risen back up to the 40-80 range. If you can get it down to around 2.5-5ppm, given the age of your tank, you can go back to your 20% weekly and monitor.

 

[JIsBusyReefing]

Alright, two things: first, grab an ultra low phosphate Hanna checker to confirm. If your phosphate is truly bottomed out, that will impact your nitrates--without phosphates, the nitrate will generally stay where it is, since most organisms need to consume both in a fairly balanced proportion. So if your phosphates are 0, your nitrate level will stop falling. Try bumping up your phosphates to 0.02 - .1 with extra feeding, or with something like Brightwell NeoPhos. Once you get your phosphates up, your nitrates will start to fall again. (But first, check your actual phosphate level with the Hanna ULR checker to verify it has actually bottomed out).

Second, if your phosphates aren't actually bottomed out, you can keep doing what you're doing, but increase either the frequency of water changes, or the volume. You could go up to something like 50% a week. 20% a week is only going to drop you from 40-80 to 30-64, which is still too high, and by the time you do your next water change, it's already risen back up to the 40-80 range. If you can get it down to around 2.5-5ppm, given the age of your tank, you can go back to your 20% weekly and monitor.

Thanks! What's your opinion on biopellet reactors for elevated nitrates? Would it be a good idea to get one if phosphate isn't bottomed out and I'm simply dealing with high nitrates? My goal is to reduce the water changes because they're a pain in the butt to do and expensive.

 

[Jonify]

Thanks! What's your opinion on biopellet reactors for elevated nitrates? Would it be a good idea to get one if phosphate isn't bottomed out and I'm simply dealing with high nitrates? My goal is to reduce the water changes because they're a pain in the butt to do and expensive.

I don't like them because it's carbon dosing you can't manage, especially if your nutrients are not sky-high. Using bio pellets in this case can bottom out your nutrients. If you want to carbon dose, I recommend using NOPOX or vinegar or vodka instead, on a doser, which will give you more fine control over how much nutrients you're removing. You can actually test for it and adjust your dose. A BRS doser for carbon dosing is like 60 bucks, and if you don't have a controller to turn it off and on, you can grab a 20-dollar-for-2 smart plug set from Amazon and set up a rule on it for how long to keep the doser on. If you're interested in that, DM me any time, and I can walk you through how I set up mine.

 

[vetteguy53081]

Nitrate /nitrate/ammonia are part of the nitrification cycle whereas phos is associated with water particle sediment.
Phosphorus is essential to the growth of biological organisms, including both their metabolic and photosynthetic processes. Phosphorus occurs naturally in bodies of water mainly in the form of phosphate (i.e., a compound of phosphorus and oxygen). However, being friends of agriculture, nitrate is not so friendly to water supplies.
You are right within the redfield ratio.
The what ??? The Redfield ratio implies that coral and bacteria consume significantly more NO3 than PO4, approximately fourteen times more. In addition, most of the methods aquarists use to reduce nutrients remove more nitrate than phosphate. This is why a nitrate deficiency is more common than a phosphate deficiency, although this does not account for the proportion of NO3 and PO4 that is being produced in the aquarium in the first place, which probably varies according to the types of food that are added.

 

[vetteguy53081]

I don't like them because it's carbon dosing you can't manage, especially if your nutrients are not sky-high. Using bio pellets in this case can bottom out your nutrients. If you want to carbon dose, I recommend using NOPOX or vinegar or vodka instead, on a doser, which will give you more fine control over how much nutrients you're removing. You can actually test for it and adjust your dose. A BRS doser for carbon dosing is like 60 bucks, and if you don't have a controller to turn it off and on, you can grab a 20-dollar-for-2 smart plug set from Amazon and set up a rule on it for how long to keep the doser on. If you're interested in that, DM me any time, and I can walk you through how I set up mine.

One has to be careful with this. Carbon can help and also hurt as coral already produces its own carbon source. Unlike bacteria, photosynthetic coral produce most of the carbon needed for growth via photosynthesis. This is the reason some aquarists add carbon sources such as vodka, sugar, vinegar and/or bio pellets because bacteria is not photosynthetic, and because much more carbon than nitrate or phosphate is required for these compounds to be consumed. Carbon becomes the limiting factor in bacteria growth . . . if your goal is to use bacteria to reduce these nutrients.

 

[Reef.]

Thanks! What's your opinion on biopellet reactors for elevated nitrates? Would it be a good idea to get one if phosphate isn't bottomed out and I'm simply dealing with high nitrates? My goal is to reduce the water changes because they're a pain in the butt to do and expensive.

Before you add anything to try and fix the problem you need to work out what has caused the problem.

Did you do a big water change after the cycle? To get your nitrates down.

Doesn’t sound like they are coming from feeding now but could have come from feeding in the past.

Over stocked with fish (I doubt it as it’s a new tank)

Cleaning sand bed and doesn’t have detritus collecting anywhere?

You need to remember that a 20% water change is only going to remove 20% of the nitrates, so,from 80 to 64 so your nitrate test is unlikely to be any different.

If my tank, I would first check I had enough biological media, the tank was clean, then Imwould do maybe 3 30% water changes to get my nitrates to around 10, then go from there, if they increase again when you are only lightly feeding and the tank is maintained well then think about adding other equipment.

But only feeding once a day is not the answer, something else is going on, you should be able to feed your fish more and still have decent levels.

 

[Jonify]

You are right within the redfield ratio.
The what ??? The Redfield ratio implies that coral and bacteria consume significantly more NO3 than PO4, approximately fourteen times more. In addition, most of the methods aquarists use to reduce nutrients remove more nitrate than phosphate. This is why a nitrate deficiency is more common than a phosphate deficiency, although this does not account for the proportion of NO3 and PO4 that is being produced in the aquarium in the first place, which probably varies according to the types of food that are added.

Yes! And keep in mind, the Redfield ratio is for natural sea water--it doesn't always hold up in our closed systems (much like anything else), but it is a great way to determine if your nutrients are available at a balanced ratio.

 

[Jonify]

But only feeding once a day is not the answer, something else is going on, you should be able to feed your fish more and still have decent levels.

This.

 

[Ippyroy]

Water changes do not affect PO4 levels. phosphate will bind to the rocks and sand. When you remove them via water changes, they will release bringing them back to the same level.
How long have you tried the methods? They can take a month or longer to see the levels change. Very few things will change in a reef tank quickly.

 

[Jonify]

One has to be careful with this. Carbon can help and also hurt as coral already produces its own carbon source. Unlike bacteria, photosynthetic coral produce most of the carbon needed for growth via photosynthesis. This is the reason some aquarists add carbon sources such as vodka, sugar, vinegar and/or bio pellets because bacteria is not photosynthetic, and because much more carbon than nitrate or phosphate is required for these compounds to be consumed. Carbon becomes the limiting factor in bacteria growth . . . if your goal is to use bacteria to reduce these nutrients.

So true. You have to be careful with carbon dosing of any kind. While some folks, like Randy Holmes-Farley advocate carbon dosing, because it helps coral uptake more nutrients than they are able to on their own, it's still risky. If you're going to do it, find a way to measure and tweak your dose to the nutrient level you are targeting. A set-and-forget option is a non-starter.

 

[HomeSlizzice]

I had the same issue with out of balance nutrient levels. As a result I had a frustrating battle with Dinos.

Here is what I would do.

-Clean out any and all detritus you can.
-doe MB7 bacteria
-dose phosphates
-be patient

 

[JIsBusyReefing]

Before you add anything to try and fix the problem you need to work out what has caused the problem.

Did you do a big water change after the cycle? To get your nitrates down.

Doesn’t sound like they are coming from feeding now but could have come from feeding in the past.

Over stocked with fish (I doubt it as it’s a new tank)

Cleaning sand bed and doesn’t have detritus collecting anywhere?

You need to remember that a 20% water change is only going to remove 20% of the nitrates, so,from 80 to 64 so your nitrate test is unlikely to be any different.

If my tank, I would first check I had enough biological media, the tank was clean, then Imwould do maybe 3 30% water changes to get my nitrates to around 10, then go from there, if they increase again when you are only lightly feeding and the tank is maintained well then think about adding other equipment.

But only feeding once a day is not the answer, something else is going on, you should be able to feed your fish more and still have decent levels.

After the cycle, my nitrates and phosphates were testing at "0" or basically near zero. I did weekly 10% water changes (no sand vacuuming) just to replace trace elements. I added a few damsels and a couple of clowns plus some clean up crew to start off, then waited a couple of weeks, added in a tang in anticipation of algae and a couple of sand sifters to deal with the diatoms I started getting on the sand, then waited a couple more weeks, then nitrate started testing at 5ppm but I didn't see it as big deal, I hit 3 months since staring up and everything was fine so I added my first corals plus some macro algae for the refugium, things were fine and added variants of fish and corals every couple to few weeks. Now, dealing with "0ppm" (according to API) phosphate and 40-80ppm nitrate, regardless of feeding low or high, and rust brown dusty material constantly grows on the sand.

My fish are:
Small assortment of damsels
x2 maroon clownfish
x1 blue tang
x1 powder blue tang
x1 sailfin tang
x2 bannerfish
x1 coral beauty angel

My corals are:
x1 small frag of yellow birdsnest
x1 frag of red montipora
x1 block of wall frogspawn
x1 head of branching reverse hammer
x1 purple gargonian
x1 small frag of duncan
x1 small frag of wall torch
x1 Kenya tree
x1 frag of Pom Pom Xenia
x1 block of GSP
x1 block of alveopora
x1 block of rainbow lobophylia
x1 frag of bubble coral
x1 fuzzy toadstool

Inverts are:
x1 large ritteri (magnifica)
x1 GBTA

CUC are:
x1 coral banded shrimp
assortment of snails
x2 sally lightfootcrabs
x1 sand sifting star
x1 conch
assortment of blue hermits

I have a very small amount of detritus collected on the monti but hardly anything.

The only thing I can think of is that the caulerpa in the fuge is eating more phosphate than nitrate. I don't have any biological filtration other than the rock work in the DT and the caulerpa.

 

[Joeg]

Is the rock porous or cement based? I ask because I struggled finding balance in my tank with Caribsea rock.

I'll share this knowing that some may find it to be an odd approach, but I like to feed heavily twice a day and prefer to have a reduced water change schedule without running a reactors etc.

What added stability for me was adding marinepure balls to the sump for additional biological filtration. Initially I added a full box for my 60 cube but it bottomed out both nitrate and phosphate within 2 weeks and I had to remove some to end up with slightly elevated levels. When I added more fish months later I was able to rebalance within about 10 days by adding a few more balls back into the sump.

I've since added a hang on Fiji Cube refugium to the side of the sump to utilize chaeto and I'm expecting that I may have to remove some balls again.

 

[JIsBusyReefing]

Is the rock porous or cement based? I ask because I struggled finding balance in my tank with Caribsea rock.

I'll share this knowing that some may find it to be an odd approach, but I like to feed heavily twice a day and prefer to have a reduced water change schedule without running a reactors etc.

What added stability for me was adding marinepure balls to the sump for additional biological filtration. Initially I added a full box for my 60 cube but it bottomed out both nitrate and phosphate within 2 weeks and I had to remove some to end up with slightly elevated levels. When I added more fish months later I was able to rebalance within about 10 days by adding a few more balls back into the sump.

I've since added a hang on Fiji Cube refugium to the side of the sump to utilize chaeto and I'm expecting that I may have to remove some balls again.

It's a combination. Some of it was cured limestone rock, some of it carribsea arches/caves/base rock, and some man made cement live rock nearly covered in coralline from my LFS.

I had looked into bio balls before but people elsewhere didn't recommend them when I was focusing on the nitrate. I'm enthused to hear that they worked that well for you!

 

[JCTReefer]

I’m curious. What nitrate test kit are you using?

 

[JIsBusyReefing]

I’m curious. What nitrate test kit are you using?

API

 

[JCTReefer]

API

Let me just say the API nitrate kit is junk! A while back I kept dosing and dosing nitrates because the API kit kept saying 0ppm. I couldn’t figure it out. Then I ordered a Nyos nitrate kit. Highly recommended!!! And come to find out, my nitrates were in fact much higher than 0ppm. More like 12 ppm. The Nyos kit is super easy to use and is pretty dang accurate! Especially in the lower ranges. I’d recommend this kit to anyone. And I’d definitely invest in the Hanna ULR. I personally like the H1-736 phosphorus checker. You do have to convert PPB to ppm, but that’s no biggie. I’d be curious to see what another kit says about your No3.