Zero Phosphates, Not sure What is Going On

[Steve2020]

Tank been going for 16mo and everything has been looking good until now. My phosphates have for the most part been between .05-.11. Last week when I checked my phosphates and nitrates ( Hanna Checkers ) my phosphate was at .02 with nitrate at 11.2. I dosed 2ml of my Trisodium Phosphate which according to my formula from James Planted Tank should raise my phosphate level by .05 per 2ml. I was told to use the Potassium Phosphate Nutrient since Trisodium Phosphate is not on the list. Mixed 1/2 teaspoon with 100ml RODI for 250gal tank. Today I checked my Nutrients and phosphate was at .01 and Nitrates at 10.2. I added 2.5ml of my solution and checked my phosphate after 2hrs from adding the solution and phosphates read 0.0. Checked twice. The reason why I checked my nutrients today was because for the first time my 40+ head Acan colony was completely deflated. I have had my Acan colony for 5mo. All other LPS doing good. I do dose the DIY NoPox and have been for 4mo and my nutrients have been stable after the first 2mo of dosing. The only things that has changed the past 3 weeks is I made my own fish food using fresh ingredients and feed twice a day. I also am feeding LRS Reef and Fish Frenzy once a day. Prior to my own fish food I strictly was feeding LRS, Mysis and some flake and TDS Pellets. LPS corals get Mysis and Fauna Marin LPS Pellets twice a week. I also am skimming more wet with my Reef Octopus Elite 220-INT. I contacted Hanna Instruments thinking I could have a bad batch of Regent so they are sending a new box of regent when they get there stock in next week. While writing this I went and checked my coral quarantine tank which I filled with 15gal of main display water when phosphate was at .06 and 5gal of fresh saltwater and I got a reading of .03 which sounds close to being correct. So lets say the regent is good, could any of my changes mentioned cause my phosphate to go to 0.00-0.01 so fast? Why after adding my Trisodium Phosphate solution did my phosphates after 2hrs not show an increase?
Sorry so long but wanted to give as much info as possible.

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Also I am on a new box of Phosphate Regent and I thought

 

[Reffetsevla]

I've battled low PO4 for a bit myself, newer tank though. Skimming wet will pull out nutrients that may need to break down in order to create the NO3/PO4. Maybe turn off your skimmer for a day or two and see if it rises, or skim dryer? I ended up removing mine entirely for a few weeks. Again though this was a much newer tank. Just sounds like your system is healthy and pulling out the nutrients, but skimming wet has also started pulling out a bit more than needed.

Also could be entirely wrong, but my exp has been to skim dryer or off for a bit if you need PO4 raised.

 

[Steve2020]

I've battled low PO4 for a bit myself, newer tank though. Skimming wet will pull out nutrients that may need to break down in order to create the NO3/PO4. Maybe turn off your skimmer for a day or two and see if it rises, or skim dryer? I ended up removing mine entirely for a few weeks. Again though this was a much newer tank. Just sounds like your system is healthy and pulling out the nutrients, but skimming wet has also started pulling out a bit more than needed.

Also could be entirely wrong, but my exp has been to skim dryer or off for a bit if you need PO4 raised.

Thank you for the response. I figured skimming wetter would pull more nutrients but I am surprised for it to pull all phosphates in 2hrs after adding a 0.06 of phosphates.

 

[Reffetsevla]

Yea I wouldn't anticipate that either honestly. Do you run a fuge? I know my chaeto has helped reduce my PO4 quickly once I managed to raise it entirely too high lol

 

[Arthur_Dent]

It's likely your tank is phosphate limited, and since you're carbon dosing, the bacteria are using phosphate fast and being skimmed out. Did Nitrate fall at all since dosing phosphate? Seems to drop 10:1 (nitrate to phosphate) in my tank, which likes to run at 0.03-0.06 po4 and 3-5 nitrate. I have to go heavy on the reef roids once or twice a week to keep po4 above zero.

Another possibility... Have you added rock or sand recently? Aragonite sand and rock will bind phosphate until it is saturated.

 

[Steve2020]

It's likely your tank is phosphate limited, and since you're carbon dosing, the bacteria are using phosphate fast and being skimmed out. Did Nitrate fall at all since dosing phosphate? Seems to drop 10:1 (nitrate to phosphate) in my tank, which likes to run at 0.03-0.06 po4 and 3-5 nitrate. I have to go heavy on the reef roids once or twice a week to keep po4 above zero.

Another possibility... Have you added rock or sand recently? Aragonite sand and rock will bind phosphate until it is saturated.

I started carbon dosing about 4mo ago because my nitrates at the time were at 18.6 and phosphates at .11. Wanted to lower them because I want to start adding SPS. Took about 2mo to see nutrients start to lower and Nitrates where lowering at about .4-.7 per week and phosphates also lowered and became stable at .04- .06. Actually I just looked at my logbook and 4 days ago my nitrate was at 11.7 and today was at 10.6 so yes I would say nitrates did drop faster than usual since I started dosing phosphates.
No new sand or rock. My fuge is bypassed since I could not keep Chaeto and that was 7mo ago.

 

[Steve2020]

Wanted to get my nitrates between 7-10 because I am LPS dominant but now I am concerned about the low phosphate. Skimmers don't remove nitrates or phosphates from my understanding they remove the organics that produce nitrates and phosphates. I may be wrong but that's my understanding. So if I skim dry like I used to or turn the skimmer off for a day or two I am assuming my nitrates will go up again which I am trying to avoid. Somehow I need to find that happy medium. Do I continue carbon dosing and just keep on adding phosphate until I get my nitrates to where I want them? If I stop carbon dosing I am assuming nutrients will rise higher than I want especially nitrates then I am back to where I started or just maybe if I stop the tank will self balance since it is more mature.
Any recommendations on these thoughts?

 

[Arthur_Dent]

I started carbon dosing about 4mo ago because my nitrates at the time were at 18.6 and phosphates at .11. Wanted to lower them because I want to start adding SPS. Took about 2mo to see nutrients start to lower and Nitrates where lowering at about .4-.7 per week and phosphates also lowered and became stable at .04- .06. Actually I just looked at my logbook and 4 days ago my nitrate was at 11.7 and today was at 10.6 so yes I would say nitrates did drop faster than usual since I started dosing phosphates.
No new sand or rock. My fuge is bypassed since I could not keep Chaeto and that was 7mo ago.

I am a believer in the power of carbon dosing. I run homemade nopox and it's fantastic. I wouldn't stop dosing. Just get a better handle on how carbon dosing (and wet skimming) affects N and P.

My recommendation would be to either add too much reef roids daily, and measure po4 and no3 daily, and record results, or dose trisodium phosphate to target 0.03 and measure daily. The latter is more "scientific". I usually just wing it....

If no3 drops along with po4 bottoming, you know you have a phosphate limited tank. Eventually, you'll hit a point where po4 starts creeping up with no drop in no3. That's equilibrium (in my opinion). From there, just feed heavier.

Hope this helps! Good luck!

 

[Arthur_Dent]

Wanted to get my nitrates between 7-10 because I am LPS dominant but now I am concerned about the low phosphate. Skimmers don't remove nitrates or phosphates from my understanding they remove the organics that produce nitrates and phosphates. I may be wrong but that's my understanding. So if I skim dry like I used to or turn the skimmer off for a day or two I am assuming my nitrates will go up again which I am trying to avoid. Somehow I need to find that happy medium. Do I continue carbon dosing and just keep on adding phosphate until I get my nitrates to where I want them? If I stop carbon dosing I am assuming nutrients will rise higher than I want especially nitrates then I am back to where I started or just maybe if I stop the tank will self balance since it is more mature.
Any recommendations on these thoughts?

Regarding skimmers and carbon dosing. My understanding is that the addition of carbon allows fast proliferation of bacteria. The bacteria eat carbon, Nitrate and phosphate. Wet skimming removes the bacteria, and by the transitive property, the phosphate and Nitrate that they recently ate.

Speaking from personal experience, I've observed that carbon dosing absolutely reduces both phosphate and Nitrate (at a ratio of around 10:1, Nitrate to phosphate). My evidence is that when phosphate is zero in my tank, Nitrate rises. Adding phosphate causes a reduction in nitrate (and vice versa, when Nitrate bottoms, phosphate rises. Adding Nitrate subsequently causes phosphate to fall).

Hope this helps you, homie!

 

[Steve2020]

Regarding skimmers and carbon dosing. My understanding is that the addition of carbon allows fast proliferation of bacteria. The bacteria eat carbon, Nitrate and phosphate. Wet skimming removes the bacteria, and by the transitive property, the phosphate and Nitrate that they recently ate.

Speaking from personal experience, I've observed that carbon dosing absolutely reduces both phosphate and Nitrate (at a ratio of around 10:1, Nitrate to phosphate). My evidence is that when phosphate is zero in my tank, Nitrate rises. Adding phosphate causes a reduction in nitrate (and vice versa, when Nitrate bottoms, phosphate rises. Adding Nitrate subsequently causes phosphate to fall).

Hope this helps you, homie!

Helps a lot and makes total sense. I have no problem adding Reef Roids. I actually stopped feeding Roids because most of my LPS have big mouths and love LPS Pellets and meaty foods. Also no issue adding Trisodium Phosphate. I was just surprised by the zero reading 2hrs after dosing it. Thought maybe had some bad regent. I have also been extremely pleased with the DIY NoPox. Only issue with it is I get some bacteria buildup in return plumbing but I have dual returns so all I do is close one return valve at a time and increasing the flow in the other and the bacteria come loose and enters the tank and my Chocolate Tang which is a pig just goes crazy and eats it all up.
Thanks for your help and recommendations.

 

[Arthur_Dent]

Helps a lot and makes total sense. I have no problem adding Reef Roids. I actually stopped feeding Roids because most of my LPS have big mouths and love LPS Pellets and meaty foods. Also no issue adding Trisodium Phosphate. I was just surprised by the zero reading 2hrs after dosing it. Thought maybe had some bad regent. I have also been extremely pleased with the DIY NoPox. Only issue with it is I get some bacteria buildup in return plumbing but I have dual returns so all I do is close one return valve at a time and increasing the flow in the other and the bacteria come loose and enters the tank and my Chocolate Tang which is a pig just goes crazy and eats it all up.
Thanks for your help and recommendations.

You're welcome! I would for sure triple check your readings if you suspect your test kits are off. Otherwise, falling params are probably normal with carbon dosing.