Why do I have high nitrates but low phosphates?

[randyBRS]

Here we go with another compelling episode of 52FAQ!

Today, Ryan sheds some light on possible causes for imbalanced nutrients in your tank, as well as briefly touches on the Redfield Ratio.

So, don your reefer thinking caps and enjoy today's episode! See you in the discussion below!

 

[revhtree]

Great info and thanks for sharing!

 

[jaws789832]

I would love to see you test Nitrate kits. I have 4 of them and they will all give a little different numbers. They are not off by a lot but enough to make me wonder which one is accurate. I had to take gfo offline because of the scenario you were describing. My nitrates were up around 10 ppt but my phosphates were always undetectable with the hanna phosphorous checker. Thanks for all the great videos and testing you are doing.

 

[Jstn]

I agree, a nitrate comparison would be useful, esp for mid and low ranges. I find myself guessing my nitrates between 10 and 25 with saliferts kit and have been thinking of trying another kit; too bad hanna doesn't have a nitrate checker ?

 

[raullbaldwin]

I have been using GFO for almost a Year and Biopellets also in a heavy bioloaded 60G reef tank with a 10 G Sump but I always have 0 ppm of Phosphates and 10 to 15 ppm o Nitrates.
PO4 Tested with Hanna
NO3 tested with Salifert and nyos.
I'm very strict with feeding mostly frozen food and very small portions of pellets and flakes
I have tried everything and can't reduce nitrates below 10 ppm
I'm installing an extra 60 G sump/refugium that will have macroalgae and a DSB.
I will exchange water between this new Sump/Refugium and the Display Tank with a Neptune DOS adjusting the amount or water exchanged until I can reach a balance.
Do you think this will solve the nitrates problem?

 

[randyBRS]

I think I see that test coming in the future...

-Randy

 

[Nano sapiens]

My 2 cents - I have been using Kalkwasser for many decades (no skimmer or mechanical/chemical filtration) and have never recorded a noticeable NO3/PO4 imbalance in any of my tanks (Salifert kits and Triton ICP for organic/inorganic phosphate). If my NO3 rose substantially, so did my PO4 by a small amount and if my NO3 declined, so did my PO4. The idea that Kalkwasser can help precipitate phosphate *may* be true to a limited extent, but IME it hasn't been detectable.

Would be an interesting experiment to show what effect, if any, Kalkwasser additions have on phosphate over time using two identically set up aquariums with the same inhabitants and feeding regimen, but one using Kalkwasser, the other 2 part.

 

[randyBRS]

I have been using GFO for almost a Year and Biopellets also in a heavy bioloaded 60G reef tank with a 10 G Sump but I always have 0 ppm of Phosphates and 10 to 15 ppm o Nitrates.
PO4 Tested with Hanna
NO3 tested with Salifert and nyos.
I'm very strict with feeding mostly frozen food and very small portions of pellets and flakes
I have tried everything and can't reduce nitrates below 10 ppm
I'm installing an extra 60 G sump/refugium that will have macroalgae and a DSB.
I will exchange water between this new Sump/Refugium and the Display Tank with a Neptune DOS adjusting the amount or water exchanged until I can reach a balance.
Do you think this will solve the nitrates problem?

I imagine by adding a large amount of additional water volume, that will be a dedicated refugium, you should notice a substantial change. If it were me, I would try to fully plumb the fuge into the main system and make it one continuous body of water. Was there a reason you were thinking of using a dosing system to move water back and forth from the display to the fuge?

-Randy

 

[burtbollinger]

my red sea nitrate test kit is strange to read, its only "accurate" if I don't place the vial on top of the paper sheet like I do with the other tests...if I lift it off of the sheet, then the color is accurate....not sure if that's what I'm supposed to be doing or what.

 

[James Kanouff]

Awesome topic BRS crew great work... Trendy BB tanks tend to have minimal anaerobic zones which leads to poor nitrate to nitrogen export abilities. Adding dark rubble zones, refugiums, or even ULTRA HIGH surface area media seems to help this issue in the absence of a sand bed for more balanced denitrification. If you use GFO, the key is having some anaerobic zones somewhere I think. Its only natural right?
I like the salifert nitrate test personally.
I now have a sulphur denitrator which is becoming a way to replace the huge Water changes, vinegar dosing and bio pellets concepts. All of which i have tried. Vinegar being the most recent and obviously effective thing i tried. The denitrator works almost too well and i have to figure how to work with that Vs a carbon source slower method. Which is what i think i will end up with and use the denitrator incase things get to far out of balance again some day. In a test I recently removed all 150 ppm of nitrate from old dirty rocks in 50 gallons of SW in a few days with a sulphur denitrator which is amazing!!! If you can handle a Ca reator and you do you home work on the topic, then there something you can handle.

 

[Cruz garza]

I use salifert and I have one nitrate and other phosphate but I still have brown algea?

 

[lodestone]

I use salifert and I have one nitrate and other phosphate but I still have brown algea?

New ?, maybe it's that new tank brown stuff, diatoms that should go away after a few weeks.

I would like to see a head to head nitrate test kit review.

 

[Broadwave]

Always great videos with great detailed info BRS! And yes, please do a video on Nitrate test kit accuracy!!

 

[bif24701]

When I started my system in Mar last year I thought near zero NO3 and PO4 was ideal however I know that is far far from the case. If it were even possible to feed corals as well as they are fed in the natural reefs, and it's not, I still believe there would be other problems with keeping NSW levels of NO3 and PO4. I had nothing but problems with NO3 <1ppm and my ideal number seems to be around 10. I try to keep the PO4 at .03 but that's difficult as I've stopped using GFO, it removes it too quickly. Now I use Phosphate RX and it's been working great. I also think the carbon part of the redfield ratio is important. With higher NO3/PO4 increased ALK/carbon is ok if not better. I have found that 10-11 dKH works well for me along with high intensity longer duration lighting. 2x Kessil AP700s and dual 60" T5 ATI Blue+, 85% 7 hours peak and 8 hour T5. That seems like a lot of light but with the AP700 there are no hot spots for my corals to get fried. I did have some bleaching issues when my NO3 was zero.

 

[Nano sapiens]

Interestingly, there are successful reef aquariums with very low NO3 and PO4 and those with relatively high levels. Considering the ratio between nitrate and phosphorus, the most accurate ratio assessment should take into account both the organic phosphate as well as the inorganic phosphate (PO4) levels, but unfortunately organic phosphate is not measurable with the typical hobbyist grade test kits.

Seems that as long as there is at least a small amount of nitrate and phosphate present, a reef system can be successful.

 

[randyBRS]

Awesome topic BRS crew great work... Trendy BB tanks tend to have minimal anaerobic zones which leads to poor nitrate to nitrogen export abilities. Adding dark rubble zones, refugiums, or even ULTRA HIGH surface area media seems to help this issue in the absence of a sand bed for more balanced denitrification. If you use GFO, the key is having some anaerobic zones somewhere I think. Its only natural right?
I like the salifert nitrate test personally.
I now have a sulphur denitrator which is becoming a way to replace the huge Water changes, vinegar dosing and bio pellets concepts. All of which i have tried. Vinegar being the most recent and obviously effective thing i tried. The denitrator works almost too well and i have to figure how to work with that Vs a carbon source slower method. Which is what i think i will end up with and use the denitrator incase things get to far out of balance again some day. In a test I recently removed all 150 ppm of nitrate from old dirty rocks in 50 gallons of SW in a few days with a sulphur denitrator which is amazing!!! If you can handle a Ca reator and you do you home work on the topic, then there something you can handle.

Whoops, I quoted the wrong message. ;-)

 

[randyBRS]

I think it's pretty hard to make real comparisons of the Redfield Ratio in the ocean versus in our reef tanks. Mostly, from my understanding, because we are talking about atoms and atomic weight comparisons of all types of nitrogen (nitrites, nitrates, nitrogen gas, ammonia, etc.) and phosphorus (organic/inorganic).

Trying to replicate these ratios in a reef tank seems to me almost unfeasible, given our hobby grade test kits and limitless factors that can skew the ratio. (I.e. phosphate content in specific foods; nitrogen and phosphate in our source water that DI cannot remove; potential nitrogen and phosphates in salt mixes, coral additives, minor/trace element supplementation; effects of nitrate/phosphate removers like GFO or NO3-PO4x that are immeasurable.)

-Randy

 

[raullbaldwin]

Thank you Randy.
I don't have the space for the new Sump/Refugium. I had to find a place and its 5 meters away and plumbing would be impossible as it would be very expensive to hide the tubing.
I'm getting a 180 G tank that will house the Sump/Refugium below and its a much better investment.
The program with DOS will exchange between DT and Sump. I think that the macroalgae and the DSB will be able to process all the nitrate and phosphate and the water returning to the DT will be almost as new. I also think that this way the S/R will not accumulate any sediments coming from the DT only perfect clean water with NO3 and PO4. This way the Chaeto and the Deep Sand Bed will eventually take care of all the nitrates and phospates tha DT can't process.
I could eventually stop using GFO and Biopellets or reduce the use of it for a more natural way.

I imagine by adding a large amount of additional water volume, that will be a dedicated refugium, you should notice a substantial change. If it were me, I would try to fully plumb the fuge into the main system and make it one continuous body of water. Was there a reason you were thinking of using a dosing system to move water back and forth from the display to the fuge?

-Randy

 

[Skynyrd Fish]

Great explanation. This makes sense to me as I have had the same problem with a 16 year old tank. I tried Vinegar and gfo for 35 weeks. Nitrates super high, PO4 almost zero. I replaced 90% of the the gravel, and was doing 30% weekly water changes. Then the Dino's and red slime won the battle. One year later I'm going with a well light fuge with cheato, and small (3% weekly) but frequent water changes. I also only scrapped the front glass clean, and am not super cleaning the tank at once, skimmer backed all the way down. Small sections per week get cleaned. I don't want to kill the red algae and have something worse take over (dino's). Im hopeful the cheato will take over and outcompete everything else. So far so good three weeks in.

Thank you for the video and explanations.

 

[Bob E]

learned something new. Thanks