With regard to Po4 how low is too low?

[Joe Batt]

Hi Randy, and other Reef2Reefers.

I have a problem that probably most reefers dream about having. I seem to have really low No3 and Po4 levels that I struggle to keep from bottoming out.

I dose NoPox in a moderately stocked mixed reef 350 Reefer, at the level of 1.8ml daily, and maintain No3 in the region of 5. The lack Nitrate seems to cause problems if it falls much below 5, and I see the system suffer, SPS especially. That said the No3 isn't concerning me overly since I seem to have the hang of that.

My problem seems to be with Po4.I have read all of Randy's posts and articles with regard to Po4 and that's where my problem seems to be. I feed 10 fish a frozen mysis cube in the morning, some nori also during the day and pellets in the early evening. I also add either 10ml of Red Sea a and B (20ml total) or a mix of ReefRoids and Coral Smoothie daily. I test my Po4 with a Hanna Phosphorus checker since the Phosphate checker just always reads zero and doesn't have the resolution I need.

I travel often and when away the tank is only getting auto pellets twice a day. When I return Phosphorus reading is often 0 ppb (Nitrate is unaffected and still around 5). If I am home and feeding as above it seems to stay around 7ppb Phosphorus (0.021ppm Phosphate). I do have a small build up of algae on the glass over a 2 day period that is very easy to scrape off, so I guess something is still in the tank to feed this growth.

If I am away for more than a few days the tank definitely suffers and starts to lose colour and some SPS suffer die off. I read in your articles that I should be aiming for a Phosphate level of 0.021ppm or less. I achieve that but if it goes below that the tank suffers.

Do you have any suggestions as to minimum levels of Phosphate for a tank and methods to achieve this without increasing the nitrates?

 

[Diesel]

Stop dosing the NoPox.
Add some flake food to the filter sock as that contains more Po4 than other foods.
Or just simple feed more, more poop is higher nutrients.

 

[teller]

Are you using GFO? Or other media?
For corals to pale you need at least one week or more of really low nutrients.
When you are out do someone feed the same amounts?

 

[Zagreus]

Bump above are you using any kind of GFO?

 

[Randy Holmes-Farley]

The phosphate is fine when you are home (0.02 ppm) and may be low when you are out.

Perhaps just upping the food when you are out will work. Dosing phosphate is easy, and could be put in an ATO if you prefer that route.

 

[dragon99]

I'm following along. Must be a reefer 350 thing, I can't seem to keep my PO4 much above 0. Last few Hanna ULR readings have been 2 (<.01)

I feel like I overfeed, because my nitrates are 10+, but I mostly feed LRS. I'll have to use more pellet/flake.

 

[sghera64]

Hi Randy, and other Reef2Reefers.

I have a problem that probably most reefers dream about having. I seem to have really low No3 and Po4 levels that I struggle to keep from bottoming out.

I dose NoPox in a moderately stocked mixed reef 350 Reefer, at the level of 1.8ml daily, and maintain No3 in the region of 5. The lack Nitrate seems to cause problems if it falls much below 5, and I see the system suffer, SPS especially. That said the No3 isn't concerning me overly since I seem to have the hang of that.

My problem seems to be with Po4.I have read all of Randy's posts and articles with regard to Po4 and that's where my problem seems to be. I feed 10 fish a frozen mysis cube in the morning, some nori also during the day and pellets in the early evening. I also add either 10ml of Red Sea a and B (20ml total) or a mix of ReefRoids and Coral Smoothie daily. I test my Po4 with a Hanna Phosphorus checker since the Phosphate checker just always reads zero and doesn't have the resolution I need.

I travel often and when away the tank is only getting auto pellets twice a day. When I return Phosphorus reading is often 0 ppb (Nitrate is unaffected and still around 5). If I am home and feeding as above it seems to stay around 7ppb Phosphorus (0.021ppm Phosphate). I do have a small build up of algae on the glass over a 2 day period that is very easy to scrape off, so I guess something is still in the tank to feed this growth.

If I am away for more than a few days the tank definitely suffers and starts to lose colour and some SPS suffer die off. I read in your articles that I should be aiming for a Phosphate level of 0.021ppm or less. I achieve that but if it goes below that the tank suffers.

Do you have any suggestions as to minimum levels of Phosphate for a tank and methods to achieve this without increasing the nitrates?

FWIW, my 180 gallon mixed reef system consistently measures 0 ppm NO3 (Red Sea Pro) and 0 ppb PO4 (ULR Hanna). I used to worry too (and see things that were not really there - Type I error).

What made it okay for me is this:
I have a macro algae refugium. Even with. 0 measurements, the algae grows enough that I must harvest it every other week or it gets too thick. I also have to clean the glass of the DT tank about every 4-6 days. AND it still have some hair algae in my frag tanks where there is low flow. I know I'm feeding phosphates and nitrates every day with my auto-feeder (pellets/flakes). That phosphate/nitrate is going into the water, but is likely being sucked up just as fast by the algae and coral before it gets to a level my assays can detect it.

You said you have algae growing on your glass. That indicates you have phosphate in the water.

Here is a question for you: you said some of your coral look "unhappy". Do you have other coral that does look happy? If so, what is that coral?

 

[Randy Holmes-Farley]

I'm following along. Must be a reefer 350 thing, I can't seem to keep my PO4 much above 0. Last few Hanna ULR readings have been 2 (<.01)

I feel like I overfeed, because my nitrates are 10+, but I mostly feed LRS. I'll have to use more pellet/flake.

Some reading is likely enough to avoid the issues of "too low" phosphate, but it is easy to dose phosphate if you want to.

 

[Reef Able]

I am following along I have exact same issue in my 150 G moderately stocked with 16 fishes mixed reef. My No3 is under 5ppm and phosphate at 0.018 and yet I have cyano and chaeto growing in my Refugium. Lately my green staghorn started loosing it's color just on couple of branches all the other sps are coloured and healthy looking. Not sure what to make of it. I used to dose Nopox up until a month ago as my Nitrates register under 5ppm. I feed pellets and flakes 4 times + 2 frozen cubes a day. If cyano and chaeto is growing tht tells me I got nutrients but not showing up on my test. I have restarted dosing Nopox as of today.

 

[Randy Holmes-Farley]

I am following along I have exact same issue. My No3 is under 5ppm and phosphate at 0.018 and yet I have cyano and chaeto growing in my Refugium. Lately my green staghorn started loosing it's color just on couple of branches everything else is coloured and healthy looking. Not sure what to make of it. I used to dose Nopox up until a month ago as my Nitrates register under 5ppm.

0.018 ppm phosphate is not too low.

Any registering nitrate is likely enough, but it can be easily raised if you need to.

 

[Joe Batt]

Thanks for all the answers

0 ppb PO4 (ULR Hanna)... This is why I use the Hanna Phosphorous checker because the Hanna Phosphate check might be reading 0 even when you are close to 0.08 in reality, due to its sensitivity and resolution.

I'm loathed to stop the NoPox because where I have it at the moment at 1.8ml keeps the No3 in check at 5 and I don't want to cure one problem only to cause another. 1.8ml for my size of a tank is pretty low. Below 5 No3 and my tank doesn't do well.
I don't use GFO or any other media besides carbon, to assist with the water clarity.
I think the feeding more route is probably the way to go firstly, and then possibly dose Po4. What are you using to dose Po4? I don't think I have seen any Po4 supplements in the LFS.

 

[Reef Able]

0.018 ppm phosphate is not too low.

Any registering nitrate is likely enough, but it can be easily raised if you need to.

Thanks Randy so u r suggesting I need to further lower my po4? I thought as far as u r between 0 to 0.03 u should be good right? With regards to Nitrates they are at 3ppm or just under. I am worried if I increase the nutrients other sps might suffer. What I don't get it is all the other sps are doing well with hood colouration EXCEPT for green stag weird. [emoji56]

 

[Reef Able]

Thanks for all the answers

0 ppb PO4 (ULR Hanna)... This is why I use the Hanna Phosphorous checker because the Hanna Phosphate check might be reading 0 even when you are close to 0.08 in reality, due to its sensitivity and resolution.

I'm loathed to stop the NoPox because where I have it at the moment at 1.8ml keeps the No3 in check at 5 and I don't want to cure one problem only to cause another. 1.8ml for my size of a tank is pretty low. Below 5 No3 and my tank doesn't do well.
I don't use GFO or any other media besides carbon, to assist with the water clarity.
I think the feeding more route is probably the way to go firstly, and then possibly dose Po4. What are you using to dose Po4? I don't think I have seen any Po4 supplements in the LFS.

Hi Joe you are right feeding more is the most natural way to increase nutrients.

 

[sghera64]

Thanks for all the answers

0 ppb PO4 (ULR Hanna)... This is why I use the Hanna Phosphorous checker because the Hanna Phosphate check might be reading 0 even when you are close to 0.08 in reality, due to its sensitivity and resolution.

Not sure how you got 0.080 (ppm?). If the ULR reads 2 (ppb Pi or inorganic phosphorus) then it would mean the sample has about 0.006 ppm phosphate.

The spec sheet in mine does say accuracy is +/- 10 ppb or +/-5% of the reading. So +/- 10ppb at the low end or about 0.030ppm.

I made phosphate standards in the past using TSP and did reproducibility and repeatability studies on my ULR. I found the precision to be +/- 3 ppb and accuracy reading consistently 3 to 4 ppb lower than the 16.5 ppb standard (25% error) that I made up. It was 8 ppb lower than the 33ppb standard (25% error).

That means the error was linear with the magnitude of the reading. What this tells me is that when I read 0-5 ppb on my ULR, my phosphate is probably <0.020ppm.

 

[zuri]

I'm not very smart but would limiting the aglae (pull more out at week) in the refuge slow the uptake? more algae in the fuge means more nutrient being absorbed less algae = more nutrient in the DT?
just thinking out loud.

 

[sghera64]

I'm not very smart but would limiting the aglae (pull more out at week) in the refuge slow the uptake? more algae in the fuge means more nutrient being absorbed less algae = more nutrient in the DT?
just thinking out loud.

Hey Zuri, don't doubt yourself. I believe you have it right. Less algae mean fewer stomata to feed (bio joke .

However, I like keeping as much macro algae as I can. I view it as a regulator. If the phosphate and nitrate in the water become limited, the algae will slow its growth.

Also, I understand that Algae release certain organic molecules that are taken up by some coral as food or an energy source.

 

[zuri]

gotcha xD

 

[Joe Batt]

Not sure how you got 0.080 (ppm?)

Sorry, I thought you were using the Hanna Phosphate checker, not the Phosphorous. With the Phosphate checker, a reading of 0 can mean the phosphate could be anywhere from 0 to 0.07ppm

 

[sghera64]

Sorry, I thought you were using the Hanna Phosphate checker, not the Phosphorous. With the Phosphate checker, a reading of 0 can mean the phosphate could be anywhere from 0 to 0.07ppm

Help me understand how you are getting 0.070ppm.

The table shows when the standard is 0.020 the ULR got 5ppb phosphorus which is 0.016ppm PO4 or 0.02ppm PO4 as BRS shows in their table on the lower right corner. They did not report the error for 0.000ppm.

 

[Joe Batt]

Help me understand how you are getting 0.070ppm.

As I said I mistakingly thought you were using the Phosphate Hanna not the Phosphorus checker. BRS tested the two against the Hok(sp?) and known strengths of Po4. At 0 the Phosphate was giving 0 and was still giving zero right up to when it gave 0.04 at 0.08 concentration. Its stated accuracy is +-0.04ppm plus minus 4% of the reading so in other words as it shows in their test it was still reading 0 even at a test level of 0.04. The resolution is 0.01 so I'm wrong in that it would probably possibly read 0 up to 0.06 as opposed to 0.07 if you take into account the +-0.04 and the further 4% of the reading error that can be present.
The Phosphorous checker which has an accuracy of +-5ppb and 5% of the reading, this equates to 0.015ppm and 5% ie much more accurate than the Phosphate checker at 0.04. The Phosphorous checker has a resolution of 1ppb which equates to 0.003ppm as opposed to the Phosphate checkers 0.01ppm.
Thes may be very low errors but such low readings they can be significant.
As your using the Phosphorus check so it doesn't matter, your getting more accurate readings anyway