In article gAiYd.70979$Tt.49598@fed1read05, Bill
wrote:

Hi all,

I'm doing a fishless cycle on my 20H tank. I've been testing ammonia
and nitrite daily, but haven't been testing nitrate very much. I
figured there wasn't any point to it until I saw nitrite, and the
nitrate test is a royal pain to do -- it's the Aquarium Pharmaceuticals
test, where you have to add 10 drops of one solution, shake the 2nd
solution for 30 seconds, add 10 drops of it, and shake the test tube for
another minute.

The last time I tested nitrate was March 4th, when I first added the
ammonia, and the result was 0 ppm. Since then, I've done daily ammonia
and nitrite tests and gotten 4 and 0 ppm, respectively. On March 6th, I
dropped some food in the water to add a little phosphate to the system,

The food could also be a source of nitrate.