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Discussion Starter · #1 ·
Hi all,

Some of the colours on the nitrate test chart look very similar and unable to pin point the exact reading. Need a second opinion.



Can you help me?


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Hi Sudhirr, does your tap water contain nitrate? If not, you can fill the tube with 2.5ml tap water and the other 2.5ml tank water which will dilute the tank's nitrate by 50%. It should shift to a different color on the chart that's hopefully easier to see then just multiply your result by 2 for actual nitrate level in your tank.

edit: your pic looks like it's in the 20-30ppm range but they don't always come out the same on a pic. Also the tube is in the shadow which makes it darker.
For me, one way I tell the difference between 30 and 40 is looking at the shade of red. 30 still has hints of orange, while 40 is pure red.
 

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Some of the colours on the nitrate test chart look very similar and unable to pin point the exact reading. Need a second opinion.
Ha ha, glad it's not just me! On my colour chart, 10 and 20 ppm are the exact same colour. @Betta Splendid's suggestion about using 1/2 tank and 1/2 'pure' water is a good one - I will try that myself, thanks!

My technique is to look at the colours either side of the 10-20ppm range and see which one I think the sample resembles most. 5.0ppm is yellowy-orange, 40ppm is noticeably reddish. So if your sample has a hint of yellow-orange then say its probably 10ppm, if it starts to have a hint of red then it's probably 20ppm. I find this helps on a couple of the API tests where the colours for two readings are hard to distinguish between. Looking at the colours on either side can give you a clue as to what colour / tint / hue you are looking for in your sample.

Realistically it doesn't usually make much difference for a planted tank if its 10 or 20ppm nitrate; they're both in the 'ok' range, at least for my tanks. I only get concerned if the test tube has an obvious red hint suggesting that nitrate is 40ppm plus and that a water change is necessary (but others will no doubt be aiming for higher nitrate, so for them red = good!)

For what it's worth, I would write down 20ppm going by your photo, but lighting could easily throw that either way.
 

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Discussion Starter · #4 ·
Thanks all for your comments.

The trending on the side of orange vs red really helps. Today I got a nitrate test which is certainly trending on the side of orange and I have listed that as 20.

A side note though. My ammonia test is light green indicating 0.25 ammonia, however if you stand that test tube for another 6-8 hours it turns yellow indicating 0 ammonia. I guess the ammonia gets degassed in that 6-8 hour period, is that right?


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Most, if not all, of the liquid test kits will change colour if you leave them past the recommended times so important to take note of the instructions. e.g. pH read immediately, ammonia / nitrite / nitrate after 5 mins, phosphate does very odd things if left. I've noticed nitrate readings in particular continue to darken over the next hour or so.
 

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The dilution idea is a good one . I got tired of shaking that damn bottle #2 and got a Sailifert Nitrate test kit . So much easier to use and no endless shaking....lol
 

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Make your life easier: use the Salifert test kit. The Sera kit is also good, but doesn't attempt to read at as many steps as the Salifert kit.
 

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For those using Salifert, why do you prefer it over API?
I'm guessing you don't like the shaking? If I don't mind the shaking part, is it still worth getting the Salifert over API?

ETA: About the ammonia test showing 0.25... There are threads on forums about this. Google "api ammonia test problem 0.25". It looks like quite a few people getting 0.25 readings when they know the water contain 0 ammonia.
 

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For those using Salifert, why do you prefer it over API?
I'm guessing you don't like the shaking? If I don't mind the shaking part, is it still worth getting the Salifert over API?
The shaking has to be done correctly for the API or the results will vary. However, this is not the biggest issue. The API results are very difficult to distinguish between 5 and ~40ppm. The Salifert kit (both fresh and salt water kits) does a better job of delineating at 5, 10 and 25ppm and the Sera is very good for 10 and 25ppm. All three are about equal above 25ppm, but there is no violent shaking requirement for the Salifert and Sera kits.

I've calibrated the Salifert and Sera at 5 (Salifert only), 10 and 25ppm and they both are on the money.
 

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The shaking has to be done correctly for the API or the results will vary. However, this is not the biggest issue. The API results are very difficult to distinguish between 5 and ~40ppm. The Salifert kit (both fresh and salt water kits) does a better job of delineating at 5, 10 and 25ppm and the Sera is very good for 10 and 25ppm. All three are about equal above 25ppm, but there is no violent shaking requirement for the Salifert and Sera kits.

I've calibrated the Salifert and Sera at 5 (Salifert only), 10 and 25ppm and they both are on the money.
I was at the lfs but they only had the saltwater Salifert test kit :(. I'm going to ask them next time if they could get the freshwater version for me as I'm also interested in the potassium test kit. I hope they could get both of them. I've seen Salifert mentioned so many times and I think it's time I give it a shot.
I hope Sudhirr is still reading this thread and considers the Salifert as he's having difficulties reading the API.
 

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I was at the lfs but they only had the saltwater Salifert test kit :(. I'm going to ask them next time if they could get the freshwater version for me as I'm also interested in the potassium test kit. I hope they could get both of them. I've seen Salifert mentioned so many times and I think it's time I give it a shot.
I hope Sudhirr is still reading this thread and considers the Salifert as he's having difficulties reading the API.
The saltwater Salifert kit is perfectly fine. I've just tested the new freshwater version and, while it uses the same chemical analysis methodology, the color chart and vial are different. However, this doesn't necessarily improve readability (I haven't decided yet - it's that close).

It is unlikely that your LFS will have any interest in potassium test kits. Only planted tanks that have picky owners (like me) are going to care and we are not a big enough market for them. I get mine here: https://www.aquacave.com/
 
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The saltwater Salifert kit is perfectly fine. I've just tested the new freshwater version and, while it uses the same chemical analysis methodology, the color chart and vial are different. However, this doesn't necessarily improve readability (I haven't decided yet - it's that close).

It is unlikely that your LFS will have any interest in potassium test kits. Only planted tanks that have picky owners (like me) are going to care and we are not a big enough market for them. I get mine here: https://www.aquacave.com/
Great! I'll grab it next time I go. Will also order the K test kit. Thanks again!
 
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