High nitrates (100 ppm) in freshly cycled tank

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Courtney Aldrich

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I just cycled my first reef tank (Red Sea 900 L including sump and refugium) and the nitrate are around 100 ppm (new Salifert kit, ran 3x and followed directions making sure to look down through the vial from the top - the solution is very pink ), which seem ridiculously high. I used RO/DI water (from LFS, but have now purchased my own RO/DI unit) and have dry rock (Marco) and dry sand (CaribSea) and haven't added any food and all rocks are new. I used Dr. Tim's method for the first time (dosed a total of 120 mL of 40 mg/mL ammonia in 2 portions) and seeded with bacteria (16 oz of Dr. Tim's). Based on the added ammonia, I would expect nitrate should be ~20 ppm. I saw Randy post that nitrites can interfere with nitrate tests, so made sure to test and have 0 nitrite. Any suggestions on potential sources of nitrate would be appreciated or is it likely that the Salifert test is over-estimating the nitrate concentration? The tank is about 4 weeks old now and I keep the lights off, so fortunately, the water remains clear (no algae growing yet). I would love to start my refugium, but Chaeto is not available.
 
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Bnutz

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100ppm seems really high. If I remember right 1ppm ammonia makes around 3.6 ppm nitrate. With 120ml of dr tims you should have less than 2ppm so nitrate should be less than 10ppm.
 
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Courtney Aldrich

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Did you cure your dry rock prior to use? I could be wrong, but I believe I read that some dry rocks can leech nitrates and other such stuff, hence the long curing process.
No, I didn't cure it. I should have checked nitrates at day 0, so I would have know what my baseline value was. The only other thing in the system is dry rock and sand, so this seems likes a potential source.
 

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As I know it - dry rocks do not leak any NO3 because there is no such compound that content NO3 that can be in the rocks. If there is organic matter in the rocks (I doubt that in dry rocks) it contain NH3/NH4 - this can be converted into NO3 in the start. But IMO - it is not likely that dry rocks content any N that can leak at all. I check your ammonia source and i content of 40 mg/ML refer to pure N. It means that your NO3 concentration (if all converted to NO3) would be 120*40*4.29/900 mg/L around 20 mg/L (or ppm) as you say)

If you are sure that your RODI water have 0 in nitrate - I would relay on the calculations not the reading because I can+t se another source. For salifert - it looks like the conversation factor according to nitrite interference is around 50 - it means that if you reading 1 mg/L as NO2 - your nitrate concentration should be around 70. You read 0.

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IslandLifeReef

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No, I didn't cure it. I should have checked nitrates at day 0, so I would have know what my baseline value was. The only other thing in the system is dry rock and sand, so this seems likes a potential source.


The only rock you need to cure is previous live rock that has been allowed to dry. In this instance, all of the live material would have died and the rock needs to cure over time to allow that dead material to be removed before putting it in a tank. Some people cure live rock for that reason as well. They allow any die off to occur in the curing process before adding it to their tank.

If your rock was truly dry rock, such as carrib sea dry rock, there is no need to cure.

I would have a trusted LFS test your water to make sure that your tests are accurate. If you tank is at those levels, then I would test your freshly made salt water before you do a water change to see if that is the source. The best way to fix your issue is with a large water change or two.
 
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Dan_P

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I just cycled my first reef tank (Red Sea 900 L including sump and refugium) and the nitrate are around 100 ppm (new Salifert kit, ran 3x and followed directions making sure to look down through the vial from the top - the solution is very pink ), which seem ridiculously high. I used RO/DI water (from LFS, but have now purchased my own RO/DI unit) and have dry rock (Marco) and dry sand (CaribSea) and haven't added any food and all rocks are new. I used Dr. Tim's method for the first time (dosed a total of 120 mL of 40 mg/mL ammonia in 2 portions) and seeded with bacteria (16 oz of Dr. Tim's). Based on the added ammonia, I would expect nitrate should be ~20 ppm. I saw Randy post that nitrites can interfere with nitrate tests, so made sure to test and have 0 nitrite. Any suggestions on potential sources of nitrate would be appreciated or is it likely that the Salifert test is over-estimating the nitrate concentration? The tank is about 4 weeks old now and I keep the lights off, so fortunately, the water remains clear (no algae growing yet). I would love to start my refugium, but Chaeto is not available.
Couple thoughts.

Since you are certain there are no nitrites, then I agree your test for nitrate is measuring nitrate. Are really sure that the nitrite kit works?

The Dr. Tim’s product you used might contain nutrients to stabilize the bacteria during storage. These could be in high enough concentration to be supplying the extra nitrogen that is being converted to NO3 and giving you the extra nitrate.

I am pretty sure the source of nitrogen is from something dosed to the aquarium. I wouldn’t turn the lights on until you got the nitrogen under control.

By the way what is your phosphate level? I expect it to be zero unless it is in the Dr. Tim’s product.
 
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Courtney Aldrich

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Couple thoughts.

Since you are certain there are no nitrites, then I agree your test for nitrate is measuring nitrate. Are really sure that the nitrite kit works?

The Dr. Tim’s product you used might contain nutrients to stabilize the bacteria during storage. These could be in high enough concentration to be supplying the extra nitrogen that is being converted to NO3 and giving you the extra nitrate.

I am pretty sure the source of nitrogen is from something dosed to the aquarium. I wouldn’t turn the lights on until you got the nitrogen under control.

By the way what is your phosphate level? I expect it to be zero unless it is in the Dr. Tim’s product.
Dan, thanks so much. I think Dr. Tim's product likely introduced the nitrates. I just found a post from last year that reported the same observation, but with much better documentation, see: https://www.reef2reef.com/threads/high-nitrates-in-new-tank.566625/. I haven't measured phosphates yet (need to buy a test kit).
 

IslandLifeReef

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Dan, thanks so much. I think Dr. Tim's product likely introduced the nitrates. I just found a post from last year that reported the same observation, but with much better documentation, see: https://www.reef2reef.com/threads/high-nitrates-in-new-tank.566625/. I haven't measured phosphates yet (need to buy a test kit).
Unless you get a confirming result from someone else doing a test on your water, I would be skeptical that your NO3 is really that high. The article you linked isn’t exactly your situation. In that case, the OP had NO2 in their tank as well.

For the Dr Tim’s product to be the source of the NO3, that product would have to have an extremely high source of N in it to raise that size of a tank up to a value of 100+ ppm. Unless you dosed around 30 ppm of ammonia over the course of the cycle, it just isn’t possible for the Dr Tims product to place that much N in your tank. The chemistry/math just doesn’t work.

My guess is you do have NO2 in your tank or have a bad test kit. An ICP test would verify this and let you know where you stand.
 

Dan_P

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Unless you get a confirming result from someone else doing a test on your water, I would be skeptical that your NO3 is really that high. The article you linked isn’t exactly your situation. In that case, the OP had NO2 in their tank as well.

For the Dr Tim’s product to be the source of the NO3, that product would have to have an extremely high source of N in it to raise that size of a tank up to a value of 100+ ppm. Unless you dosed around 30 ppm of ammonia over the course of the cycle, it just isn’t possible for the Dr Tims product to place that much N in your tank. The chemistry/math just doesn’t work.

My guess is you do have NO2 in your tank or have a bad test kit. An ICP test would verify this and let you know where you stand.

I agree about the 0 ppm nitrite. Should be reconfirmed.
 
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Courtney Aldrich

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Unless you get a confirming result from someone else doing a test on your water, I would be skeptical that your NO3 is really that high. The article you linked isn’t exactly your situation. In that case, the OP had NO2 in their tank as well.

For the Dr Tim’s product to be the source of the NO3, that product would have to have an extremely high source of N in it to raise that size of a tank up to a value of 100+ ppm. Unless you dosed around 30 ppm of ammonia over the course of the cycle, it just isn’t possible for the Dr Tims product to place that much N in your tank. The chemistry/math just doesn’t work.

My guess is you do have NO2 in your tank or have a bad test kit. An ICP test would verify this and let you know where you stand.
I reconfirmed my nitrate at my LFS 2 weeks ago at 100 ppm. I just tested my nitrate today and they're down from 100+ ppm to 10-25 ppm, so it looks like I have some denitrifies finally colonizing my tank. I had suspected Dr. Tim's product was the source of high nitrates since I only dosed about 5 ppm of ammonium chloride, which would give about 18.5 ppm of nitrate (nitrate weighs 3.7x that of ammonia). I contacted Dr. Tim's and never heard back from them. However, after further thought on the subject, I realize it's highly unlikely that Dr. Tim's would be source of nitrate. For a 900 L system at 100 ppm, I would have 90 grams of nitrate, and I cannot imagine the bottle would have this much nitrate. So, I have no idea what caused by high nitrate readings initially. Some people had rightfully suspected nitrites, but my Salifert nitrite tests always showed 0 ppm nitrite. I'm happy to see my nitrates have come down and guess the best thing I did was patiently wait. I had almost decided to do a 900 L water change to bring the nitrate down.
 
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Courtney Aldrich

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The high nitrate reading is caused by high nitrite (different spelling). Without zero nitrite, nitrate meanings are pointless.
"Without zero nitrite, nitrate meanings are pointless". I don't understand this statement. Can you clarify. I had zero nitrites and now have 10-25 ppm nitrate.
 

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I reconfirmed my nitrate at my LFS 2 weeks ago at 100 ppm. I just tested my nitrate today and they're down from 100+ ppm to 10-25 ppm, so it looks like I have some denitrifies finally colonizing my tank. I had suspected Dr. Tim's product was the source of high nitrates since I only dosed about 5 ppm of ammonium chloride, which would give about 18.5 ppm of nitrate (nitrate weighs 3.7x that of ammonia). I contacted Dr. Tim's and never heard back from them. However, after further thought on the subject, I realize it's highly unlikely that Dr. Tim's would be source of nitrate. For a 900 L system at 100 ppm, I would have 90 grams of nitrate, and I cannot imagine the bottle would have this much nitrate. So, I have no idea what caused by high nitrate readings initially. Some people had rightfully suspected nitrites, but my Salifert nitrite tests always showed 0 ppm nitrite. I'm happy to see my nitrates have come down and guess the best thing I did was patiently wait. I had almost decided to do a 900 L water change to bring the nitrate down.
Something still does not make sense. How does a system lose nearly 100 ppm in less than two weeks?
 
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Something still does not make sense. How does a system lose nearly 100 ppm in less than two weeks?
I don’t know. The tests aren’t that accurate. I should buy one of the nice Hanna digital photometers. It went from a dark pink to a much lighter color on the Salifert kit. I tested 5 times at 100 ppm, so I think the reduction is real.
 
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