When you are testing your water with the drop test kits, it says to hold the tube in front of the white of the test card. Not to sound stupid, but do you hold it right against the white part or only in front of it? The reason I ask is that the color looks darker when it is held close and lighter farther away. I want to make sure I am reading these tests right.

Hi,

I think it means the white bit.

Not a stupid question at all.

Slugger

Should I hold the tube flush with the white part i.e. touching it or should I hold the tube in front of it with space between the tube and the reader card? How close I hold it to the test card changes the darkness and possibly the results of the test

Basically the way they're designed is that you hold the card in one hand and the tube up to the white card so the white background is flush at the back of the tube (in a well lit room). The reason I believe is it gives a truer indication of levels...

So for example, if your testing for nitrates - while holding the tube up to a light, it may appear they're very low but when you hold it against the white background under said light, it's a bit darker than first suspected.... so time to do a waterchange

I hope this helps

A lot depends on the amount of light in the room. As I have been led to understand, an ideal situation for reading these tests are in a full sunlight situation with the sun shining on the front of the tube and the white background pressed against the back of the tube. Since most of us do not have full sunlight at our beck and call, we have to compromise a bit. Use the best full light you have. If you have less that ideal light, it has been suggested that you pull the tube away from the card by a bit to allow light to enter the tube from all sides. Bymoving the tube back and forth, in and out, you can come to a compromise as to the reading.

Keep in mind that these tests only give an approximation of the ppm of various inclusions. That is why they give a range for each level - it is somewhere within that range, but cannot be quantified any more exactly than the human eye can see.

An approximation is usually good enough to give you an idea where your water parameters are.

Thanks for the excellent info. It seems so simple but a little variation can do alot to the tank. I really appreciate your attentive answers to this simple question. You are great!!