Carbon Dosing having no effect on Nitrates?

[Randy Holmes-Farley]

Also, according to the article I posted above - if I’m remembering it correctly - carbon dosing effects nitrates versus phosphates 16 to 1, respectively. So, you should see a much greater reduction in nitrates from dosing.

Sort of.

It ignores denitrification, which uses only nitrate, but yes, growing organism tissues use far more nitrate (or other N) than phosphate.

The exact ratio varies some between organisms, and the 16:1 (Redfield Ratio) is the N atom ratio, not nitrate (NO3-) to phosphate (PO4---). Phosphate weighs more, so it isn't 16:1 nitrate to phosphate, but closer to 10.5 : 1.

 

[ClownSchool]

Sort of.

It ignores denitrification, which uses only nitrate, but yes, growing organism tissues use far more nitrate (or other N) than phosphate.

The exact ratio varies some between organisms, and the 16:1 (Redfield Ratio) is the N atom ratio, not nitrate (NO3-) to phosphate (PO4---). Phosphate weighs more, so it isn't 16:1 nitrate to phosphate, but closer to 10.5 : 1.

Thank you. Good to know.

 

[optimisticdingo]

@Hans-Werner @Randy Holmes-Farley So I reconducted my tests this evening as well as tested Nitrite.

Nitrite was Zero, Nitrate appeared to be about 40, and Phosphate still tested Zero. I used a different cuvette to try and rule out any issues with the previous cuvette.

At this point I'm just wondering if I should just do large water changes to get the Nitrates down. However, I'm not sure what the best way would be to go about doing that. I've never conducted larger than a 30% water change. Do you guys have any other suggestions?

 

[Reef - Tripp]

Poor Man's Nutrients Control - Donovan's Nitrate Destroyer

Hello fellow reefers!. I have been in the hobby for more than 3 years, the first 2 years was tough. Cyno, diatom, nuisance algae, high NO3 (120ppm at one time) and ich/velvet. I have tried several nutrient control method (poor man, so most of it were DIY project). GFO, water fall scrubber...

www.reef2reef.com

 

[RGoltz]

I'll redo the phosphate test this afternoon as well. However, I conducted the test the same way that I normally do. I use the Hannah Phosphate checker and make sure to shake the cuvette for a solid 2 minutes on a timer before placing it into the checker.

I use 1 cuvette for the test and I make sure to clean the cuvette with a microfiber cloth before placing it into the checker wether that be zeroing out the checker or doing the test once reagent is added.

I believe the proper procedure is to shake for 60 seconds and then hold the button to activate the 3 minute timer on the checker. At least that is how I do but check the instructions to be sure.

My experience with carbon is similar to other posts meaning NO3 drops faster than PO4. I think 16:1 sounds right. But once your PO4 is limited you will find NO3 sort of gets stuck. In that case, I had to dose PO4 to lower NO3!

I also dose bacteria (Prodibio) and although I have no proof, I think this yields a good bacterial balance to manage nutrients.

 

[Hans-Werner]

Nitrite was Zero, Nitrate appeared to be about 40, and Phosphate still tested Zero. I used a different cuvette to try and rule out any issues with the previous cuvette.

At this point I'm just wondering if I should just do large water changes to get the Nitrates down. However, I'm not sure what the best way would be to go about doing that. I've never conducted larger than a 30% water change.

I am a bit surprised since I was quite convinced that the result is an artifact.

Yes, water changes are always a good solution to getting rid of nitrate. Since all of the nitrate is in the water you should see immediate succes. In my opinion it is not necessary to do more than 20 % water changes. It is better to do every change slowly, so corals can adapt.

Even changes to the better may have negative effects if they are too fast and corals have not time to adapt.

 

[Reefahholic]

Maybe there is a phosphate testing problem?

Yes, what is he using for PO4 test?

 

[Reefahholic]

Sort of.

It ignores denitrification, which uses only nitrate, but yes, growing organism tissues use far more nitrate (or other N) than phosphate.

The exact ratio varies some between organisms, and the 16:1 (Redfield Ratio) is the N atom ratio, not nitrate (NO3-) to phosphate (PO4---). Phosphate weighs more, so it isn't 16:1 nitrate to phosphate, but closer to 10.5 : 1.

What would you say is a decent N to P ratio? Seems like everybody has different numbers. Obviously we want Nitrate higher, but just how high is the question. I’ve seen people run at 3ppm and up to 50ppm with amazing tanks.

 

[elysics]

The numbers fit carbon dosing working well don't they? Phosphate going from 0.2 to 0, Nitrate going from somewhere in the middle between 40-65 to 40, that's maybe even working a little better than it should. Phosphate just ran out

You might need to raise phosphate though, heavy water changes probably aren't going to get it any higher either

 

[optimisticdingo]

Yes, what is he using for PO4 test?

Hanna Phosphate checker. The HI713 version

 

[ecrumpler]

I had a 125g FOWLR for years that had gotten out of hand with Nitrates. They were literally "off the chart" on the Red Sea test kit. I started carbon dosing and for months I didn't see a difference so I kept upping the dose. I did this until there was a tipping point with huge bacteria blooms and an eventual sharp drop down to almost zero. It took forever to move my nitrates down, but once they started moving, it was real obvious. Perhaps your nitrates are higher than your test kit says or you have something, i.e., sandbed or rock, that is producing nitrates at a high rate.

 

[Reefahholic]

Hanna Phosphate checker. The HI713 version

Check your reagents and see if they still have good expiration dates. Also…look into the Hanna Phosphorus ULR. It will read down lower and you may have some phosphate present.

 

[optimisticdingo]

I feel like the reagents would still be good. I recently purchased them. Maybe not even a month old

Check your reagents and see if they still have good expiration dates. Also…look into the Hanna Phosphorus ULR. It will read down lower and you may have some phosphate present.

 

[Reefahholic]

Did you check expiration dates. Sometimes companies sell them already expired. Just a thought.

I feel like the reagents would still be good. I recently purchased them. Maybe not even a month old

 

[optimisticdingo]

Did you check expiration dates. Sometimes companies sell them already expired. Just a thought.

I'll check them once I get home

 

[Randy Holmes-Farley]

What would you say is a decent N to P ratio? Seems like everybody has different numbers. Obviously we want Nitrate higher, but just how high is the question. I’ve seen people run at 3ppm and up to 50ppm with amazing tanks.

I do not consider ratios important, only absolute values.

IMO, phosphate is good in the 0.02 to 0.1 ppm range, and nitrate in the 2-10 range.

 

[Randy Holmes-Farley]

Hanna Phosphate checker. The HI713 version

"Phosphate still tested Zero."

That checker cannot verify that phosphate is too low.

A zero reading can be as high as 0.04 ppm and not be out of perfect specifications.

 

[optimisticdingo]

"Phosphate still tested Zero."

That checker cannot verify that phosphate is too low.

A zero reading can be as high as 0.04 ppm and not be out of perfect specifications.

I'll look at getting the Ultra low range checker

 

[Reefahholic]

I do not consider ratios important, only absolute values.

IMO, phosphate is good in the 0.02 to 0.1 ppm range, and nitrate in the 2-10 range.

Perfect. That’s about exactly where my tank run. Although I try to stay .05-.1 on PO4 and NO3 seems to do well anywhere from 3-8 for me. I might explore slightly higher valves maybe up to 25 this time just to see the affects on the corals.

 

[Piker]

"Phosphate still tested Zero."

That checker cannot verify that phosphate is too low.

A zero reading can be as high as 0.04 ppm and not be out of perfect specifications.

Perfect. That’s about exactly where my tank run. Although I try to stay .05-.1 on PO4 and NO3 seems to do well anywhere from 3-8 for me. I might explore slightly higher valves maybe up to 25 this time just to see the affects on the corals.

Resurrecting because I'm curious as to how this played out. This is identical to my current experience with carbon dosing. I've just started 3 days ago with NO3PO4X. I have been able to repeat the results for 3 days. Going into the two-hour block where carbon is dosed (1/4 reccomended dose currently) I test, and during lighting ramp down I test again.

My pre-dosing tests have been a consistent 12-18 nitrates (not my goal, aiming for 10), and .06-.1 phosphates. The phosphates are at this higer level each day because I'm dosing them up every evening. I'm using both hanna checkers and salafert test kits just because it didn't make sense to me.

Of note: GFO has been shut off after the first 0.00 Phosphate reading the first day, I recently phased out a (very clean) refugium, so that could contribute to the higher nitrates. I'm not seeing much nitrate reduction at all. I'm wondering if there is just something weird about my system and I should stick with it until things even out? Has anyone else had experience like this?

Trying to add to the discussion here, rather than start a new thread because I'm not seeing much more information on this. So weird!