Water testing how to

[cginflorida]

This may sound like a silly question, but when you're doing water tests, and you hold the test tube up to the color reference card, do you put the tube right ON the card or hold it slightly above it? It makes a big difference in color, and therefore the results.

I'm using Aq. Pharmaceuticals test kits, and I've always put the tube right up against the card. It just occurred to me that I might be doing it wrong. The directions don't really make it clear.

[lmw80]

I use Aquarium Pharmaceuticals as well, and I always hold it an inch or so away from the card. It may actually say that on the directions (the paper ones, not the one on the back of the color card), but I am at work right now and can't double check it.

[cginflorida]

Originally Posted by lmw80

I use Aquarium Pharmaceuticals as well, and I always hold it an inch or so away from the card. It may actually say that on the directions (the paper ones, not the one on the back of the color card), but I am at work right now and can't double check it.

The paper instructions just say to hold it against the white area of the card, which doesn't necessarily mean touching it. Anyway, I just sent an email to Aq Pharm asking them about it.

I'm fishless cycling right now, and I don't want to wait any longer than I have to - but I want my new fishies to be safe when I get 'em. 8)

[Christmasfish]

The color card matches refers to HUE not saturation..
so if it looks the same but lighter? it is the same

It is still either looks bluer or greener (or redder to more yellow) no matter if it is light, whitish, or dark (dark sure makes it easier)

Holding next to or away really should NOT change the hue, only the saturation.
Though I believe the tube is to be held ON the card


(when in doubt I always use the LaMotte kit I bought in a panic before going to an lfs)

[tmurphy171]

I use the Red Sea test kit. It states on the instructions for this brand of kit to hold the tube 8 inches away against a white background. I read the results in natural daylight. I've found the color changes abit when viewing in incandescent or fluorescent light.

[cginflorida]

Got my answer back from Aquarium Pharmaceuticals. They said to hold the tube against the card. Good point about the hue, Christmasfish.

Thanks, everyone.