Nitrate tests with Salifert kits

[Str8linespeed]

Hello RC,

I just did my water tests using Salifert kits and when I tested my Nitrates, they were 10ppm. Three days ago they were only 5ppm. I repeated the test today and it came in again at the same. I grabbed my API test kit and checked. It read 0 ppm, rechecked and same results 0ppm. Now keep in mind I just did a 10gal. in my 65gal. tank last Monday. I have no dead snails, fish or coral that I have found.

I've always been curious about the Salifert kits. They have never read zero and always about 5ppm.

Last time I had higher reading like this, I decided to let me LFS check to see if it was something i was doing. There test resulted in 0ppm, Im not sure what kits they were using but they were in small blue dropper bottles.

Are the Salifert kits accurate??

[RegalAngel]

What method of testing for Nitrate did the LFS use?

[Str8linespeed]

What method of testing for Nitrate did the LFS use?

Like I said, Im not sure but I just saw of my water to a vial. They then put in so many of the first drop, then added the second set of drops. Im assuming it was similar to the API kit, but in blue bottles.

[bertoni]

There are several issues here. Nitrate kits in general have a fairly poor reputation for accuracy. In addition, the Salifert kit is designed to avoid interferences from amines in the water sample, so it often reads higher than other kits. The API kit does not handle amine interference, as far as I can tell. Personally, I'd trust the Salifert result, but 0-10 ppm is a fine range for most systems.

[Dan_P]

Hello RC,

I just did my water tests using Salifert kits and when I tested my Nitrates, they were 10ppm. Three days ago they were only 5ppm. I repeated the test today and it came in again at the same. I grabbed my API test kit and checked. It read 0 ppm, rechecked and same results 0ppm. Now keep in mind I just did a 10gal. in my 65gal. tank last Monday. I have no dead snails, fish or coral that I have found.

I've always been curious about the Salifert kits. They have never read zero and always about 5ppm.

Last time I had higher reading like this, I decided to let me LFS check to see if it was something i was doing. There test resulted in 0ppm, Im not sure what kits they were using but they were in small blue dropper bottles.

Are the Salifert kits accurate??

Using the Salifert color chart to tell the difference between 5 and 10 ppm is a close call. The pink shades are very close. So, that's one issue you are having.

A rise in nitrate over several days would not be an impossibily even without dead bodies around. Denitrification can slow or stop and nitrates would start accumulating.

The API nitrate test does not do well with low nitrate concentrations. It performs best at higher nitrate levels.

It is possible that your nitrates are 5-10 ppm. How old is your system?

[Str8linespeed]

Using the Salifert color chart to tell the difference between 5 and 10 ppm is a close call. The pink shades are very close. So, that's one issue you are having.

A rise in nitrate over several days would not be an impossibily even without dead bodies around. Denitrification can slow or stop and nitrates would start accumulating.

The API nitrate test does not do well with low nitrate concentrations. It performs best at higher nitrate levels.

It is possible that your nitrates are 5-10 ppm. How old is your system?

First off, thanks to all that have replied.

I also view it from the side and then divide by 10. It was easily the color of the 100 on the chart. I have a hard time looking straight down from the top and differentiating the colors. Same issue with the pO4 test. I cant see any difference and you can only do that test one way.

I thought about doing a 20gal WC this weekend to get the nitrates back down. I have a mixed reef with SPS, LPS and Soft, along with fish. So if you think 10ppm isnt bad maybe I'll just another 10gal.

This system is just over 3 months old, so yes very young yet.

[bertoni]

You could try another water changes, although I suspect that 10 ppm is fine. You might find that the nitrate level jumps back up fairly quickly after a water change. That's very common.

[Str8linespeed]

You could try another water changes, although I suspect that 10 ppm is fine. You might find that the nitrate level jumps back up fairly quickly after a water change. That's very common.

I did another 10gal WC this morning. I'll test later this afternoon and see how things looks.

[tmz]

I've always been curious about the Salifert kits. They have never read zero and always about 5ppm.


Mine reads zero( clear from the top and side view) much of the time.

[bertoni]

If the Saifert kit detects nitrate in distilled or RO/DI water, that's a reasonably good indication that it's not working anymore.

[Str8linespeed]

If the Saifert kit detects nitrate in distilled or RO/DI water, that's a reasonably good indication that it's not working anymore.
I didnt get around to the water test to see how the tank looks. I do my water tests every 3 days. Tomorrow is day 3. I will also run one test with my makeup water to see how it turns out. Thanks for that tip.

[Dan_P]

If the Saifert kit detects nitrate in distilled or RO/DI water, that's a reasonably good indication that it's not working anymore.

I wonder if this is a correct statement.

The test chemistry cannot generate the colored diazo compound without nitrite being present. If the kit goes bad, I presume the reducing reagent is the thing that stops working, i.e., nitrate not being reduced to nitrite, making a kit "fail" colorless, not giving a false positive.

If RO/DI is giving a positive test, I am pretty sure nitite or nitrate are present.

[Str8linespeed]

Alright I did another 10gal. WC on Saturday, tested today and my Nitrates are still at 10ppm.

I did do a test with my makeup water and that was 0ppm.

I have to believe that the Salifert kit is accurate and Im actually @ 10ppm. Thanks again for the responses. I do have some minor algae in my tank and it could be dying off and contributing to the rising nitrates. I'll probably do another WC on Wed. to try to knock them back down. Just waiting for my new RO membrane to come in before I make more water.

[bertoni]

I had some Red Sea test kits that failed and read nitrate in everything. I'm not sure what chemistry they were using, but it was an interesting effect.

[Dan_P]

I had some Red Sea test kits that failed and read nitrate in everything. I'm not sure what chemistry they were using, but it was an interesting effect.

Interesting.

The current Red Sea nitrate kit reduces nitrate with zinc followed by diazotization. I cannot think how it can form the diazo dye unless there is nitrate or nitrite present. Contamination might be a reason or there really was nitrite/nitrate everywhere. Were you dosing with nitrate at the time?

[bertoni]

No, I was setting up my first aquarium, and the nitrate never reached zero, so I tested some distilled water and some RO/DI. Maybe my memory is going: it was a long time ago, but I remember having the ammonia and nitrate kits fail.