Nitrogen cycle questions
I planted a tank last month. I ended up getting a second tank and planted that one too. A few days ago I got a betta for tank #2. I've been obsessively testing his water. The day after adding the betta, ammonia was 0, nitrite was 1, and nitrate was 5. Did a 30% water change + Prime. Day after that I had same readings: 0 ammonia, nitrite 1, nitrate 5. 30% water change + Prime. Day after that ammonia 0, nitrite .25, nitrate 5. Next 2 days ammonia and nitrite were 0, nitrate I'm gonna say 4 (not quite the 5 color).
Is it because of the plants that I never got an ammonia reading? Is it because of the Prime that my nitrites reduced to 0? Is my cycle complete since I have 0 ammonia, 0 nitrite, and 4 nitrate?
Also I want to add fish to tank #1 soon. On tank #2 (betta tank) I have an HOB that came with the tank and I also have a sponge filter. My plan is to remove the HOB and just keep the sponge filter in there, but I want to make sure the HOB collects some beneficial bacteria first so that I can transfer it over to tank #1. WHEN should I do that? Only after I add fish? A couple days before I add fish? I believe if I transfer it too early with no ammonia source in tank #1 the bacteria will die. ?