High nitrates (100 ppm) in freshly cycled tank

Reef. · Mar 5, 2021

Is your nitrites on zero? If not when you do a nitrates test any nitrites present in the tank will be counted as nitrates, you need a zero nitrites test to get a correct nitrates reading.

Once at zero you will get a lower nitrates reading.

Courtney Aldrich · Mar 5, 2021

Garf said:
Yes, I failed to read your previous posts, soz. What’s the problem?

I thought you had some more insight and I misunderstood. I'm still confused on what's happening. As Dan_P says, something still isn't right. I've seen several other threads with similar experiences with 100 pm nitrates using Dr. Tim's and dry rock, but very few have a final outcome, so I want to document my experience

Courtney Aldrich · Mar 5, 2021

Reef. said:
Is your nitrites on zero? If not when you do a nitrates test any nitrites present in the tank will be counted as nitrates, you need a zero nitrites test to get a correct nitrates reading.

Once at zero you will get a lower nitrates reading.

I did have zero nitrites on my old as well as a new Salifert test kit. I tested many times - always colorless. It seems more plausible as you suggest that the high readings must be due to nitrite interference. This in turn would indicate a bad test kit rather than a 100 ppm drop of nitrates in two weeks.

saltedbytes · Mar 24, 2021

Just want to chime in on this thread.

I have had the exact same issue. Fresh cycle, dry rock, Carib sea sand, Dr Tim’s, Salifert Ammonia and Nitrite test at 0 and yet the Salifert Nitrate test is off the charts.

RO water tests 0 and have run each test multiple times with the exact same result.

Reef. · Mar 24, 2021

saltedbytes said:
Just want to chime in on this thread.

I have had the exact same issue. Fresh cycle, dry rock, Carib sea sand, Dr Tim’s, Salifert Ammonia and Nitrite test at 0 and yet the Salifert Nitrate test is off the charts.

RO water tests 0 and have run each test multiple times with the exact same result.

What’s your nitrite reading? If it’s not zero you will get a high nitrates reading as the nitrate test reads nitrates as nitrite so any nitrites will be counted as nitrates.

saltedbytes · Mar 29, 2021

Reef. said:
What’s your nitrite reading? If it’s not zero you will get a high nitrates reading as the nitrate test reads nitrates as nitrite so any nitrites will be counted as nitrates.

Nitrite is 0

Have been testing every day for the past week, just like the OP my Nitrates are now starting to come down. Nitrite is 0 every time.

Reef. · Mar 29, 2021

saltedbytes said:
Nitrite is 0

Have been testing every day for the past week, just like the OP my Nitrates are now starting to come down. Nitrite is 0 every time.

did you add the correct amount of ammonia? And are you 100% sure that nitrites are zero?

1ppm of nitrites can give a reading of as much as 100 ppm nitrates.

If you can remember all the ammonia you have added (maybe see how much is missing from the bottle) you can work out how much nitrates that ammonia produced, 1ppm produces around 3.5 times the nitrates.

Not a big deal, a 100% water change will get you to a near enough zero nitrate lvl, if you have fish or corals do the changes in maybe 3-4 changes.

Randy Holmes-Farley · Mar 29, 2021

saltedbytes said:
Nitrite is 0

Have been testing every day for the past week, just like the OP my Nitrates are now starting to come down. Nitrite is 0 every time.

Can you clarify how you tested nitrite and what value "0" means it is less than? Less than 1? less than 0.1?

saltedbytes · Mar 31, 2021

In total I've added approximately 80ml of Dr Tim's ammonium chloride over several weeks.

So if my calculations are correct, with a water volume estimate of 500L (roughly accounting for rocks and sand), that would equate to raising the Ammonia by a total of 3.2ppm which would only equate to 12ppm nitrate?

For the Nitrite testing, I am following the instructions included by Salifert exactly. The test result comes out absolutely clear which going by the card is 0ppm Nitrite.

Reef. · Mar 31, 2021

saltedbytes said:
In total I've added approximately 80ml of Dr Tim's ammonium chloride over several weeks.

So if my calculations are correct, with a water volume estimate of 500L (roughly accounting for rocks and sand), that would equate to raising the Ammonia by a total of 3.2ppm which would only equate to 12ppm nitrate?

For the Nitrite testing, I am following the instructions included by Salifert exactly. The test result comes out absolutely clear which going by the card is 0ppm Nitrite.

I get more than that, 80ml is around 1600 drops, at 4 drops per US gallon that's 528 drops to get to 2ppm, means you added around 6ppm with is about right as you are meant to do 3 doses, so hopefully if my maths are correct you should be around 20ppm nitrates?

Randy Holmes-Farley · Apr 1, 2021

saltedbytes said:
In total I've added approximately 80ml of Dr Tim's ammonium chloride over several weeks.

So if my calculations are correct, with a water volume estimate of 500L (roughly accounting for rocks and sand), that would equate to raising the Ammonia by a total of 3.2ppm which would only equate to 12ppm nitrate?

For the Nitrite testing, I am following the instructions included by Salifert exactly. The test result comes out absolutely clear which going by the card is 0ppm Nitrite.

To make sure you understand my question for future interpretations of test results...

Saying you have zero of some chemical in a reef tank is never true.

The result of a test kit may be closer to zero than the next highest value that the specific test kit can read, and thus the reading is "less than" whatever the lowest readable nonzero value is. What that value is depends a lot on the test kit used, and it makes a big difference whether that means less than 0.5 ppm, less than 0.1 ppm, less than 0.01 ppm, etc.