Why no nitrates!!!

Sallstrom

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The cited text above says, that with 1 - 2 µmol/l the N uptake is saturated, which means the coral just can't take up more N than at this concentration, further increase doesn´t make any sense. 2 µmol is 36 µg or 0.036 mg of NH4+ or 62 µg or 0.062 mg of Nitrate. Nitrate levels in coral reefs are not much higher than Phosphate levels, in average about 2.5 times higher by weight, this means around 0.04 ppm, and corals show net nitrate uptake.
Everything else you see at higher nitrate concentrations is not a positiv effect of nitrate uptake but rather a sign of stress.
Hi Hans-Werner!
David here, from Gothenburg. Thank you for a great talk at MACE :)

In the ocean corals get some of their N from feeding on different types of plankton. That part is probably lower in most aquariums. Could it be possible they need to take up more N in an aquarium than on the reef because of that?

Also, isn't a risk to get too low when aiming for natural N levels? How do we keep a steady level of NH4 in an aquarium?
 

Hans-Werner

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Hi David,
it was nice to meet you in Rosmalen! Always good to see someone in person!

The saturation constant Vmax is a biochemical constant. Feeding doesn´t matter. The coral just can´t take up more nitrate at higher concentrations than at Vmax. It is like you want to feed or drink more but you just have one mouth, no matter how much food or drinks is around you. The corals have ion pumps and channels for uptake of nutrients in their cellular membranes. If they are saturated you just can't increase the rate of pumping with higher concentrations.

If there is a N deficiency in corals the brownish color of the zooxanthellae gets extremely light, more yellowish of even whitish. As long as this is not the case there is no N deficiency in this coral.
 
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Shinte122305

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And you are really shure the nitrate is the cause and not 0.1 ppm of phosphate? Did you do controlled experiments? In my experience phosphate is important for good fluorescent colors. Of course bright fluorescent colors look even brighter on a dark brown coral but the nitrate does nothing for the coral. The uptake of the coral for nitrate is much much more than saturated at 5 ppm or even 2 ppm. In most corals uptake should even be more than saturated at 1 ppm. It just can't take up more nitrate than at these concentrations. That is very basic biochemistry.
If I ever will find the time I will upload an image that shows that Stylophora 'Milka' can also look good if it is brightly colored with pink and bluish hues instead of purple on dark Brown.

No, I am not sure I am an engineer not a chemist but I got 10 years of experience growing corals and I take care of my friends frag tank weekly and with that I’ve learned a ton about getting coral growth and coloration.

I don’t know if it’s specific to nitrates but I’ve tried the 0 nitrates super low phosphate way and everything got washed out and barely grew. I tried dosing nitrates alone and that made my phosphates go to 0 and nothing looked happy it seams that dosing nitrates lowers phosphates and the same happened the other way around maybe I’m crazy.

The best results happened when we read an article that a dude had good results with high nutrients so we tried it we added more fish, removed the GFO, started skimming very dry to keep nutrients in the water but we wanted the skimmer for the ph buffer, we started to feed the tank like crazy including coral food and we started doing much less water changes. We focus on calcium and alk to stay stable we don’t do anything about ph it just does it’s thing and the phosphates and nitrates shot up.

The tank started doing incredible. Zoas growing like weeds everything coloring up . At this point we put any coral in the tank and it colors up and grows within weeks it’s phenomenal. We have well over 10k in beautiful corals in a nice and dirty tank like people call it. Maybe it’s not specific to nitrates but they are there and they are always above 10.

Only one time I saw the nitrates get to 25 and I started getting algae so I had to do an extra water change nothing happened to the corals.
 

Hans-Werner

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There is nothing wrong with your experience or your observations. High nutrients are ok, only that nitrate usually is overestimated, especially regarding the concentrations. 1 ppm of nitrate is more than sufficient for the corals. If more is needed to fend off cyanos it is a different matter which has nothing to do with the needs of corals. In almost no tank there is any need to dose nitrate for the well-being of the corals.

In my eyes greyish colors and a bad polyp extension is quite typical for phosphate deficiency in corals, which may be quite widespread. As the citation above states the uptake kinetics of P and N compounds are similar. Since the molecular weight of PO4--- is 95 g/mol and "the threshold concentrations at which the consumption starts are within 0.1-0.2 µmol -l" a net phosphate uptake starts at ca. 10 - 20 µg/l or 0.01 to 0.02 ppm phosphate.
 
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AlexG

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In my experience the production of nitrates can be naturally achieved if the correct conditions are available to produce excess nitrate levels. In my first saltwater tank I struggled with high nitrates 80+ppm for years until I finally understood that my methods of filtration were causing the problem. My high nitrate issues were related to having canister filters and quick sand filters. The quick sand filters are from the 1990s and are similar to a fluidized bed filter. Both of these types of filters were nitrate factories as they were very efficient at breaking down waste to ammonia->nitrite->nitrate but they were not efficient in breaking down nitrates to N2, N2O, or other nitrogen compounds. Filters that trap waste, have a large surface area, and lots of oxygen available have a higher likely hood of producing excess nitrates. The resulting imbalance in the nitrogen cycle allows excess nitrates to build up because of the lack of adequate denitrification to keep nitrates balanced. A large portion of denitrification takes place in anaerobic conditions, where the bacteria that consume nitrates thrive. When I finally defeated my nitrate issues and got the levels under control I made a denitrification filter that provided surfaces area for bacteria in an anaerobic which balanced out the nitrogen cycle in my system. Since you are faced with the opposite problem and you would like to increase nitrates you can try to create an imbalance in the nitrogen cycle that produces excess nitrates. Some methods that might work for this would be using filter socks or filter pads and just leave them in place without being changed or cleaned. Add a canister filter with filter pads and/or biological media and neglect the cleaning filter. As with any change to a system I would caution to take it slow, observe your tank inhabitants, and closely monitor water parameters.

Regarding the utilization of nitrates by corals I am no expert in that process nor have I read and of the documentation cited in this thread. I would like to add to this conversation though as I find it to be an interesting topic. One thing I have learned about reef aquariums throughout the years is that the number of variables in the mix at any one time is vast. Considering the vast number of variables it can be difficult to understand why a change in nitrate levels even if its minor creates an observation of increased coral health or growth. While nitrates might not be consumed directly by the corals there is a potential that the increased nitrate level impacts other life in your aquarium which might benefit the corals. As a theoretical example lets say that a minor increase in nitrate levels allows the natural phyoplankton and micro algae population to increase, which in turn creates a larger food supply for other mico and macro fauna such as copepods which as a result of a larger food supply increase in population. Increased populations of micro and macro fauna means that the number of organisms breeding will be increased due to the higher population. As these small organisms breed they will release eggs and sperm into the water or in some cases larval stage organisms or small adults will also be free swimming in the water column. All of this small life has a chance to to captured and consumed by corals as food which can benefit the corals. Again that was just a theoretical example but it can't be ruled out that increased nitrate levels can impact other organisms in an aquarium system which can directly benefit coral health.
 

Hans-Werner

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QUOTE="Hans-Werner, post: 5414247, member: 72725"]If I ever will find the time I will upload an image that shows that Stylophora 'Milka' can also look good if it is brightly colored with pink and bluish hues instead of purple on dark Brown.[/QUOTE]
I hope I will manage to show the image. This is a Stylophora `Milka´. I think it looks different from most `Milkas´ you have seen yet. It can also be brown with blue tentacle tips but I think the natural color (like it was imported originally) is more like this pink with bluish tentacle tips. The conditions are bright daylight-alike LED lighting, low nutrients, regular supply of calcium, alkalinity and trace elements. It is photographed exclusively with the aquarium illumination, white balance at daylight, no flash used. As you can see it is a diffuse lighting a bit warmer and less blue than usual.
Milka15.1.19K.jpg
 

Ashish Patel

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In my experience the production of nitrates can be naturally achieved if the correct conditions are available to produce excess nitrate levels. In my first saltwater tank I struggled with high nitrates 80+ppm for years until I finally understood that my methods of filtration were causing the problem. My high nitrate issues were related to having canister filters and quick sand filters. The quick sand filters are from the 1990s and are similar to a fluidized bed filter. Both of these types of filters were nitrate factories as they were very efficient at breaking down waste to ammonia->nitrite->nitrate but they were not efficient in breaking down nitrates to N2, N2O, or other nitrogen compounds. Filters that trap waste, have a large surface area, and lots of oxygen available have a higher likely hood of producing excess nitrates. The resulting imbalance in the nitrogen cycle allows excess nitrates to build up because of the lack of adequate denitrification to keep nitrates balanced. A large portion of denitrification takes place in anaerobic conditions, where the bacteria that consume nitrates thrive. When I finally defeated my nitrate issues and got the levels under control I made a denitrification filter that provided surfaces area for bacteria in an anaerobic which balanced out the nitrogen cycle in my system. Since you are faced with the opposite problem and you would like to increase nitrates you can try to create an imbalance in the nitrogen cycle that produces excess nitrates. Some methods that might work for this would be using filter socks or filter pads and just leave them in place without being changed or cleaned. Add a canister filter with filter pads and/or biological media and neglect the cleaning filter. As with any change to a system I would caution to take it slow, observe your tank inhabitants, and closely monitor water parameters.

Regarding the utilization of nitrates by corals I am no expert in that process nor have I read and of the documentation cited in this thread. I would like to add to this conversation though as I find it to be an interesting topic. One thing I have learned about reef aquariums throughout the years is that the number of variables in the mix at any one time is vast. Considering the vast number of variables it can be difficult to understand why a change in nitrate levels even if its minor creates an observation of increased coral health or growth. While nitrates might not be consumed directly by the corals there is a potential that the increased nitrate level impacts other life in your aquarium which might benefit the corals. As a theoretical example lets say that a minor increase in nitrate levels allows the natural phyoplankton and micro algae population to increase, which in turn creates a larger food supply for other mico and macro fauna such as copepods which as a result of a larger food supply increase in population. Increased populations of micro and macro fauna means that the number of organisms breeding will be increased due to the higher population. As these small organisms breed they will release eggs and sperm into the water or in some cases larval stage organisms or small adults will also be free swimming in the water column. All of this small life has a chance to to captured and consumed by corals as food which can benefit the corals. Again that was just a theoretical example but it can't be ruled out that increased nitrate levels can impact other organisms in an aquarium system which can directly benefit coral health.


Wow,, I learned something new today and it makes sense... time to add some dirty socks!!!!
 

DesertReefT4r

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I have a 3 year old reef tank that refuses to produce nitrates and I am not sure why.

Salifert nitrate test shows zero,...the water is as clear as ro/di when viewed from the top or sides and I am sure this is why I am having slow SPS growth and fight bleaching if my alk gets near or above 8dkh.

It is a 50g. with 8 fish I feed very heavy and I also feed reef chili a few times a week. I do not grow macro or dose any thing to lower nutrients and have a cheap protein skimmer I run dry. I do have a small amount of matrix in my sump but mainly just so the pods have somewhere to hang out.

I have tried dosing nitrates(stump remover) and that bottomed out my nitrates, I tried feeding more and that just raised my phosphates.

I change 5 gallons of water every 2 weeks and I use kalk in my top-off water for alk/cal. Doesn't take much when nothing is growing.:p

test results as of last night;
cal.-410
alk.-7.7
nitrates-0
phosphates-.09

I feed rotate daily feeding 1/2 cube PE mysis/1/2 cube spiralina brine shrimp, new life spectrum pellets. I have some fat fish!

I really do not want to have to dose nitrates and phosphates. So what are my options?
More fish? Less water changes? Take the skimmer off line?

I have never seen a tank that would not produce nitrates and I have had a few down through the years!:)
I am having the same thing happening with my current 75g reef tank. It has not had detectable no3 since a few weeks after the nitrogen cycle finished. Went from 10ppm on API to undetectable so I figured it was just in the 3-1 ppm range. Got Red Sea Pro kits and no3 is still undetectable. I do have a small fuge, a decent large skimmer running dry and filter sock that is changed every 3-4 days. I have decent bioload and feed well even increased feeding but all that seems to be doing is causing me to clean my glass more.
Test as of last Saturday
Temp 77.9
Ph 7.86
Salinity 1.025
Alk 8.1 dkh
Cal 410 ppm
Mag 1600 ppm thanks Fritz RPM never need to dose that one
No3 0.0 ppm
Po4 0.08 ppm
Some systems just seem to do really well at processing no3. My last 2 reef tanks also always had undetectable no3. I ended up removing my fuge in my last tank and that increased no3 to round 10ppm but i also ended up with bubble algae issues after a while.
 

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