Low(ish) nitrates but high phosphates

Letterkenny

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My phosphates keep tending to be a bit high with them running at 0.17ppm most recently (typically 0.07-0.12ppm) with nitrates usually around 5ppm. While not off the chart, I’m curious why I can’t get my phosphates lower. I’m not running GFO as I was hoping my chaeto reactor would be doing the bulk of the reduction there but I’m really not seeing much growth. Should I start occasional GFO or any ideas to kick start chaeto growth?
 

rmurken

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you might explore whether you’re nitrate-limited. Your chaeto and other photosynthesizers might not be able to use the excess PO4 without more NO3.

I have been in this situation once or twice and used good old stump remover (potassium nitrate) to goose my NO3 a bit. Seemed to help—PO4 came down. My PO4 was not as high as yours. I like stump remover because, well, it’s called “stump remover,” and I like to be not-fancy. But there are nicer reef-specific nitrate supplements out there.

My approach was to go slowly—add a few ppm of NO3, wait a day or so, check PO4 and NO3 to see if both were falling, then do another round of NO3.

Others have done it too—you can definitely find old threads about it.

And the usual compulsive caveat you surely do not need—go slow. PO4 is not necessarily the worst thing ever, and if you’re not having a problem (eg algae or coral growth), consider having a beer and enjoying your tank instead of tweaking numbers.
 
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Letterkenny

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you might explore whether you’re nitrate-limited. Your chaeto and other photosynthesizers might not be able to use the excess PO4 without more NO3.

I have been in this situation once or twice and used good old stump remover (potassium nitrate) to goose my NO3 a bit. Seemed to help—PO4 came down. My PO4 was not as high as yours. I like stump remover because, well, it’s called “stump remover,” and I like to be not-fancy. But there are nicer reef-specific nitrate supplements out there.

My approach was to go slowly—add a few ppm of NO3, wait a day or so, check PO4 and NO3 to see if both were falling, then do another round of NO3.

Others have done it too—you can definitely find old threads about it.

And the usual compulsive caveat you surely do not need—go slow. PO4 is not necessarily the worst thing ever, and if you’re not having a problem (eg algae or coral growth), consider having a beer and enjoying your tank instead of tweaking numbers.
I’ll test my PO4 again tomorrow. My best is that it will be closer to .08ppm. I checked it a day after feeding reef roids which always skyrockets my PO4 for a couple days. Currently fighting algae growth and just trying to get the refugium going. Been using chaetogrow and still haven’t seen massive growth in my reactor like I have read people have.
 

rmurken

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I’ll test my PO4 again tomorrow. My best is that it will be closer to .08ppm. I checked it a day after feeding reef roids which always skyrockets my PO4 for a couple days. Currently fighting algae growth and just trying to get the refugium going. Been using chaetogrow and still haven’t seen massive growth in my reactor like I have read people have.
Ah, algae. Hopefully the chaeto will help you out once it kicks in. Mine just sat around and didn’t do much for a long time, and then it just started growing. It’s modest growth, but I have a modest bioload, so it seems about right. Doesn’t stop all algae in my tank, but seems to slow it down to where snails and maintenance keep it in check.
 
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Letterkenny

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Ah, algae. Hopefully the chaeto will help you out once it kicks in. Mine just sat around and didn’t do much for a long time, and then it just started growing. It’s modest growth, but I have a modest bioload, so it seems about right. Doesn’t stop all algae in my tank, but seems to slow it down to where snails and maintenance keep it in check.
Yea my sand bed in particular is getting crushed. I have a yellow diamond goby that’s almost done with QT to hopefully help. Have probably 20 nassarius snails (but 15 are baby’s) and two tiger conches but my sand bed isn’t turning over. Thinking about a sand sifting starfish but they don’t eat algae so they?
 

Randy Holmes-Farley

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I don't really think these values are a substantial issue.

The "why" isn't likely worth focusing on. There are many processes that add or subtract only one of them.

Do you dose trace elements such as iron that the chaeto might benefit from?
 
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Letterkenny

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I don't really think these values are a substantial issue.

The "why" isn't likely worth focusing on. There are many processes that add or subtract only one of them.

Do you dose trace elements such as iron that the chaeto might benefit from?
I’ve been adding chaetogrow to the tank to hopefully stimulate growth.
 

blasterman

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Reef Roids is a clear 'guilty' in my experience with phosphate.

Still, I'm wondering what the source of phosphate is here given I feed occasionally Roid's and I can't keep so much a trace of it in my tanks unless I really dose the 'Roids or add Seachem Fertilizers. I've always suspected a lot of montipora growth as eating up phosphate.

Softies and LPS don't seem to have a problem with 5-10ppm nitrate (if I turn my skimmer off) and zero phosphate, but it clearly presents problems for SPS.
 
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Letterkenny

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Reef Roids is a clear 'guilty' in my experience with phosphate.

Still, I'm wondering what the source of phosphate is here given I feed occasionally Roid's and I can't keep so much a trace of it in my tanks unless I really dose the 'Roids or add Seachem Fertilizers. I've always suspected a lot of montipora growth as eating up phosphate.

Softies and LPS don't seem to have a problem with 5-10ppm nitrate (if I turn my skimmer off) and zero phosphate, but it clearly presents problems for SPS.
I have a mixed reef tank. Everything seems fine for the most part (my torches like the higher phosphate). I’m just annoyed about the algae growth on the sand and want to be cognizant of my SPS. (FYI - I got rid of the cyano in this older pic).

7BD61783-8E0D-4E77-BA25-AFCB336ACFF5.jpeg
 

rmurken

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How old’s your tank? Can’t tell but looks like it could be newer? If so, sometimes the solution is waiting it out. A few months at least of growing various cycles and phases of undersea flora seems to be normal.
 

Pistol Peet

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Brightwell Aquatics makes a Chato fertilizer also time your lights are on either increase or decrease the hours they're on as needed to fit your needs GFO is okay to run especially if you have a Predator Tank as they tend to produce more waste product gfo works exceptionally well though so only use it as an as-needed basis do your testing get it down using the gfo then watch it when your numbers start to increase you add new gfo if your numbers are staying stable you know the GFo was working
 

Daddy-o

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Brightwell Aquatics makes a Chato fertilizer also time your lights are on either increase or decrease the hours they're on as needed to fit your needs GFO is okay to run especially if you have a Predator Tank as they tend to produce more waste product gfo works exceptionally well though so only use it as an as-needed basis do your testing get it down using the gfo then watch it when your numbers start to increase you add new gfo if your numbers are staying stable you know the GFo was working
I have not noticed GFO (or Phosguard) as having any significant impact on my phosphates. Added a couple drops of LC and they go down nicely.
Cheers! Mark
 

Daddy-o

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You didn't use enough or for long enough, in that case. :)
I ran a reactor loaded with GFO (and lately PhosGuard) all day, every day for over 2 years, changing out for new every 4 days. Didn't seem to make a difference but I kept at it thinking it would work at some point.
Cheers! Mark
 
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Letterkenny

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Brightwell Aquatics makes a Chato fertilizer also time your lights are on either increase or decrease the hours they're on as needed to fit your needs GFO is okay to run especially if you have a Predator Tank as they tend to produce more waste product gfo works exceptionally well though so only use it as an as-needed basis do your testing get it down using the gfo then watch it when your numbers start to increase you add new gfo if your numbers are staying stable you know the GFo was working
I’ve tried that, didn’t work for me. I don’t run GFO as I wanted the chaeto to do the work there
 

Randy Holmes-Farley

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I ran a reactor loaded with GFO (and lately PhosGuard) all day, every day for over 2 years, changing out for new every 4 days. Didn't seem to make a difference but I kept at it thinking it would work at some point.
Cheers! Mark

It cannot "not work', but it can certainly be insufficient in amount or in water contact to meet the need to lower phosphate. :)
 

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