To start, I do know a bit about how the nitrogen cycle is supposed to work, and previously I have cycled a tank with the expected results. That is, I add some ammonia (from the hardware store) plus a bacterial supplement like Seachem Stability or Tetra Safe Start. After a while, nitrites show up, and finally everything gets converted over to nitrates. I have even cycled bio media alone in a jar, and it takes about two days.
This time, I have set up a tank with UNS Controsoil, some dwarf hairgrass, marsilea crenata, moss, and a rotala something. It's been about a month now, and I still don't get the expected results. What happens is I dose 1-2 ppm ammonia, and over about 1-2 days, the ammonia disappears, but at no point do I ever see nitrites or nitrates. The plants are growing out, and there are various splotches of algae and diatoms everywhere, so I do know that stuff is happening.
I also tried the cycle-in-a-jar with similar results. I had a heater set to 80F and water with pH 7+. At one point, I think I saw 5 ppm nitrates, but then half a day later, ammonia/nitrite/nitrate were all zero again.
Here's the parameters for the new tank, with some things being different than the old tank, so maybe one of these is the culprit:
- pH mid-upper 6's. (UNS Controsoil like to buffer in the low 6's, but I added a touch of bicarbonate to bring it up a little)
- temp 80F
- Water is RO + Salty Shrimp GH + a little KHCO3
- 5000K light for about 8 hrs a day, plus several more hours of indirect lighting
- Dose both Seachem Stability and Tetra Safestart
- Half dose of Seachem Excel every other day
- Light water flow with aeration
- Using API master test kit