it would be very low though. 3 guppies i would estimate would generate about 2-3ppm ammonia in a 10g per week. try not changing the water for a while. you can keep a tank TOO clean. If you remove the ammonia before it can be metabolized you are hindering the cycling process.
I could be wrong though. I am basing this on 3 fullgrown swordtails in a 10g generated about 15-20ppm per week. This came from my first tank where i didnt bother doing research first. twice daily water changed got very old and i still lost 2 of the swords. I only do fishless cycling now.
Most bottle tests lose accuracy at the high range and are more sensitive at low end (easy to see on the cards). Bottom line is if ammonia or nitrite change color at all there is too much in the water.
