ap test kit

[miles]

The other day I finally got an AP master test kit and tried it out. I noticed that there is a drastic difference in how the color looks when held touching the card and held in front but with space between. The lensing/shadow effect between the card and the tube when they're touching makes it appear an entire shade darker than it is when held ~2 inches away. Lighting isn't an issue.

So this might be a really silly question, but which is the correct way to look at the test? Is it the color when the tube is held away from the card (which is the tube's "transparent" color) or the color when it's touching the card which is a whole shade darker? The instructions say view it "against" the card", but I also have left over test strips and their results are close to the results I see when the tube is held away from the card.. that's why I'm asking.

 

[Convict2161]

I place my test tubes on top of the plastic cover that the kit comes with, that's how I read my results. I don't put it against the white. It's always gonna be darker that way. Just make sure you have good lighting. That's how I do it anyway.

Hope that helps.

 

[miles]

Thanks. I guess what I want to know is whether the color card is calibrated for the darker color or the lighter color. So you're saying it's the lighter color I should be going by. The directions are a little misleading when they say read the color "against" the white part of the card - it doesn't mean literally touching the card, it's just saying "compare it against the colors on the card". I'm thinking too much into it.. as usual.

In any case, it will become obvious which I should be reading after my tank finishes cycling. Right now my water params are all over the place, and 2 ppm nitrite vs 4 ppm makes a big difference when you're waiting for it to drop!

 

[Coryluv]

After a lot of testing and reading it both ways, I hold the tube about 1/4 in. in front of but not touching the white portion of the card. It is the nitrate test that I have the most trouble reading, but seeing it now from a low of 0 (testing my tap water) to a high of 40 ppm (when I didn't know it was getting that high because I didn't shake solution #2 enough), I definitely say not touching the card.

 

[miles]

The nitrate test was the one I was having the most trouble with actually. Has yours ever given a false negative? The first time I tested my nitrate (following the directions to the letter) it was 20, then the next day it said it was 0! I tested it three times with well-rinsed and dried tubes and I shook the living daylights out of that bottle number two, but it kept coming back yellow, which I knew was impossible. The next day it was 20 again. I never did figure that one out. I'm a little paranoid about the nitrate test reliability now. I know the AP kit is the "best" one out there right now though, and it hasn't given me any problems since.

Anyway, I think you're right about holding the tube slightly away from the card. Of course, the exact nitrate value isn't crucially important for most established tanks, but it can be when your tank is cycling and you're (not so) patiently waiting to get your fish! I wonder how many people have done water changes because they read the nitrate as a shade darker than it actually is

 

[Convict2161]

I learned from this site and I'm glad I did. Don't over think it. Test it, put it down and take your readings. You can drive yourself crazy TRUST ME!! The guys/ gals here will tell ya, I drove myself crazy for a while being new. I think I've come along way.

Also look at your fish, they can tell you a lot. Are there fins close to there body? Are they not as active? Hiding? Not eating? The test is good and I test everyday. But just sit back and watch your fish. They'll let ya know.

Enjoy.

 

[Coryluv]

About the false negatives, I've never gotten a 0 except on my tap water, but have gotten the famous 5 on the nitrate for not shaking enough. I know it was wrong because I had four tests in a row at 5 and the next one was at 40. The day I got the 40 I had shaken the heck out oI number 2. I was also starting to see the brown algae return which I now take as my nitrate early warning system even without the test. Needless to say I really shake the number 2 hard now.

 

[Coryluv]

PS. One more thought. I'd rather do a "needless" water change for reading the nitrate too dark than to miss one for reading it too light. I'm a big believer in water changes. They solve a multitude of problems and unless you don't match temp or forget the Prime (or whatever you use), they do much good.