How do you compare colors on API Saltwater Master test kit?

NinnJinn · Mar 31, 2018

I started cycling my tank yesterday with ammonium chloride.
I decided to do a nitrite and nitrate test just a few minutes ago and I guess my eyes are not what they used to be because I was referring to my 13 and 11 year old daughters for color comparisons.

On the nitrate my daughters are saying it's 10ppm.

So based on the above pictures is this how you compare colors? Or do you hold the tube over the colors and whichever one matches perfectly as the right way?

So are my daughters correct in that my nitrates is 10PPM?

saltyfilmfolks · Mar 31, 2018

I squint my eye a bit , and look at the contrast between the colors.

The last pic is easier to do it with.

I’d go with 5-8. Ish.

Jesterrace · Apr 1, 2018

Ah, the lovely API nitrate test kit. Now you know why many of us switch over to Red Sea, Salifert, etc. since API makes their test so close that it's tough to tell apart pretty large variances in ppm. Did you make sure to shake the bottle really well before doing the test?

40B Knasty · Apr 1, 2018

+1 on color variations being to close. Looks like it is between 5-10ppm.
I would also like to had to a problem with the API test tube. The laser etched print of the white 5ml line can be way off. Pickup a 5ml syringe. Extract the water you are choosing to test. Then squirt it in the glass test tube and don't pay attention to the line. I recommend ELOS test kits. Watch this video at 3 minutes in. Showing you how off the laser etched 5ml line is.

sergifed91 · Apr 8, 2018

I moved away from the APImaster test kit. kept getting false readings with the ammonia test. I ended up going to the LFS and had them test my ammonia, PH nitrate and nitrate. everything was spot on except for the Ammonia test. so I ended up buying the api test strips. and now i'm getting more accurate readings for the ammonia test now. but still using the master kit for PH, Nitrate and Nitrate. so far so good.

Jesterrace · Apr 8, 2018

40B Knasty said:
+1 on color variations being to close. Looks like it is between 5-10ppm.
I would also like to had to a problem with the API test tube. The laser etched print of the white 5ml line can be way off. Pickup a 5ml syringe. Extract the water you are choosing to test. Then squirt it in the glass test tube and don't pay attention to the line. I recommend ELOS test kits. Watch this video at 3 minutes in. Showing you how off the laser etched 5ml line is.

Yup, discovered that one when I borrowed an extra syringe from my Red Sea Test Kit for my API Freshwater Test kit (the exact same as the saltwater with a slightly different color chart). I had to go to 6-7mL on the syringe to reach the 5mL mark on the API vials. Add in the leaky caps (nothing better than splashing caustic chemicals all over you when you shake), and the lack of variation in the nitrate color chart and it is all in all a bad deal. Oh and the skinny vials are lovely to clean.

Joshua M Hall · Jun 16, 2018

Can someone tell me if you actually hold it "against" the white paper or do you hoover it off the white a bit? I notice if I hold it against it and it is touching I get a slightly darker color. So for example when reading PH it looks like a slightly higher reading if it is touching then if I hold it off a hair. What do you guys recommend. I know in the instructions it says "against" but I don't know if they are being literal or not.

jasonrusso · Jun 16, 2018

Joshua M Hall said:
Can someone tell me if you actually hold it "against" the white paper or do you hoover it off the white a bit? I notice if I hold it against it and it is touching I get a slightly darker color. So for example when reading PH it looks like a slightly higher reading if it is touching then if I hold it off a hair. What do you guys recommend. I know in the instructions it says "against" but I don't know if they are being literal or not.

I hold the card in my left hand and the vial in my right hand at arms length in front of my white fridge.

lejeune981 · Jun 16, 2018

I have a devil of a time reading them.. being color blind in the red spectrum..
IF I use a color chart.. I call the girlfriend over to tell me lol
Slowly but surely.. I'm converting over to Hanna instruments

Joshua M Hall · Jun 16, 2018

Thanks for the reply guys. But I think my main question is do you press it against the white background or hover it just off. Jason from your answer I take it that you don’t hold it against the paper. Unfortunately my fridge is stainless. Haha

Johniejumbo · Jun 16, 2018

I hold it away from the paper a little bit. I can be a little tough to tell but if you can peg which color it looks like it’s probably somewhere right between those 2 colors. I like the api tests myself. I just don’t rely on them for spot on accuracy just good general range. I will say that my ammonia test went a little screwy too. Kept reading ammonia when I was fairly certain there wasn’t any. LFS confimed it.

glb · Jun 16, 2018

API isn’t super accurate but I’ve always used it during cycling because it’s less expensive. Once measuring low levels of nitrate is important, I switch to Salifert. I’m thinking of trying Eos because the Salifert colors are hard for me to tell apart too!

40B Knasty · Jun 17, 2018

glb said:
API isn’t super accurate but I’ve always used it during cycling because it’s less expensive. Once measuring low levels of nitrate is important, I switch to Salifert. I’m thinking of trying Eos because the Salifert colors are hard for me to tell apart too!

You won't be disappointed with ELOS. It is accurate and the colors are so easy to tell apart. Especially the pH. I have the Pro Phosphate and Nitrate kits as well. Highly recommend!