Color Change WHILE reading my test tube

[BillyZ]

ok, hopefuly some of you with the salifert test kits can back me up on this. I'm currently cycling a 55 tank for a refugium. All thats in it currently is southodwn sand, water, two sock balls of LS from my established aquarium and one shrimp (looking a lot like a fur ball now...)

as expected, my ammonia is climbing but now I'm not sure of the exact level because I don't know if I'm reading my test kit right. Don't laugh, I'm serious.

I put in the water and the chems and let it sit as instructed by the kit. When I picked it up to read it I thought to myself, "hmm seems kinda low, would have expected it to be higher by now... ah well, slow cycle" Then, as I was turning to put down the test card I noticed the color in the tube CHANGE. I picked it back up.. it changed BACK. 8O (I'm not crazy!)

after a second or two of blinking my eyes I figured out what was going on. the only light in the area with the fuge is a single incandesent bulb. If i'm facing the bulb with the test kit infront of me, the tube was reading low.. around .5; If I turned around with the bulb behind me and the kit in front of me, the kit reads high 1.5... so which way should I face to read it?! 8O

 

[alrmc4]

good question and i know exactly what you are saying not sure if i am doing it correctly but i take the water into the kitchen to test so i can read it by the light coming in the window...looking forward to finding out the proper way!!!!

 

[reefrunner69]

When you set it down you are losing light to portions of the vial. Trust the reading holding it in front of you and putting the color card behind it. You'll notice the same thing on the tests where you sit it on the whit portion of the card and view the test from above. If you hold it just a little above the card the reading is different. I read a post by Habib (owner of Salifert You can actually post to hi on RC in the chemistry forum) on RC once where this question was asked and he stated the test was calibrated to be sitting on the card...not above it.

 

[BillyZ]

stated the test was calibrated to be sitting on the card...not above it

That part I got. My dilema is on where the lightbuld is. Once i had it figured out, I held the ammonia vial up against the card while facing the light:

8O [vial]|card|

and it read about .5.

Holding the vial that way and watching the color of the vial, I slowly turned around. AS I turned around the color of the liquid in the vial got darker as the light got more directly behind me:

8O [vial]|card|

it then read 1.5

turning back towards the way I started I could watch the color get lighter again. Thats a BIG color difference and a big difference in the reading.

 

[reefrunner69]

The light should probably be directly overhead.