I've been doing a fishless cycle with biospira for exactly 2 weeks now. Everything has made sense so far. I started dosing ammonia the first day and watched the levels slowly go down. Dosed 3-4ppm whenever ammonia reached less than 1ppm. After 4 days I saw nitrites in the water. Eventually I had a nitrite spike and then nitrites slowly came down to less than 0.25 ppm. I just did a 80% water change in hopes of putting my first batch of fish in tomorrow or Wednesday. I just checked my nitrite level and it is a little more than 2ppm! 8O How is this possible? I have no nitrites out of the tap. For the water change I used a python and took out 80% of the water. Then I added 1 1/2 capfuls of Seachem Prime (its a 75 gallon tank) to the remaining 20% of the water and filled it back up. If anyone has an explanation or any ideas about this I would love to hear from you. TIA!