Red Sea NO3 test inaccurate?

[ianryd]

I'm testing nitrates in my new tank. Had a quick cycle since I used rock and sand from my current tank. I'm making sure its ready for fish, because the first Salifert test I did after cycling showed 50ppm nitrates. I've changed 60 gallons of water to bring them down. I did 4 tests with 3 different kits. after the WC Here are my results-
Red Sea NO3 Pro high range 0.0
low range 0.75
Salifert between 5 and 10
API 10

I usually test with Salifert but wanted to compare it to a few others. I'm more inclined to believe the salifert and API since their results are closer. I'm just wondering why the red sea is wildly lower. Every time I use it it seems way lower than my other kits. All test kits are within expiration. I know either way its safe enough to add fish, but It takes like 10 minutes to test and costs way more than my other tests, so I'm just wondering if anyone else has experienced similar results with the Red Sea.

 

[mike550]

I've never used Red Sea, but have used both API and Salifert. I've come to trust Salifert and have had others test my water and had similar results. That said, I recently switched to NYOS because the test was easier to read than Salifert.

 

[Dan_P]

I'm testing nitrates in my new tank. Had a quick cycle since I used rock and sand from my current tank. I'm making sure its ready for fish, because the first Salifert test I did after cycling showed 50ppm nitrates. I've changed 60 gallons of water to bring them down. I did 4 tests with 3 different kits. after the WC Here are my results-
Red Sea NO3 Pro high range 0.0
low range 0.75
Salifert between 5 and 10
API 10

I usually test with Salifert but wanted to compare it to a few others. I'm more inclined to believe the salifert and API since their results are closer. I'm just wondering why the red sea is wildly lower. Every time I use it it seems way lower than my other kits. All test kits are within expiration. I know either way its safe enough to add fish, but It takes like 10 minutes to test and costs way more than my other tests, so I'm just wondering if anyone else has experienced similar results with the Red Sea.

When you obtain a “0” it can be “0” or a bad test. The first step In Red Sea test with vigorous shaking for 1.00 minutes is important. Red Sea is usually reliable and cosistent.

 

[ianryd]

I got the 0 reading on the high range test which measures 4 ppm and above, so I figured it was because the reading was lower than 4. I shook the ba-jeezus out of it and followed the directions closely. Maybe I'll try again tonight.