Silent cycle turned fishless...

[Fishy_Dan]

Hello,

I've got a heavily planted 15g tank that has been running for 10 days. Plants are doing well, salvinia now takes up around a quarter of the surface, hygrophilia and limnophilia both growing well.

I've been monitoring my water parameters and ammonia had been present at a low level (0.25-0.75ppm), I assume as a result of decaying plant matter as they adjust to the tank. I added quick start after a few days and now nitrite levels are quite high, I tested half tap/half tank water and it came out around 2-4ppm. So the tank nitrite levels must be approaching 10ppm.

Ammonia is now 0, I'm not adding any, so I assume the plants and bacteria are now able to handle the ammonia load released by decaying plants. So what should I do about the nitrite? Leave it for the bacteria to grow and then come down? Or do a water change to get it to a lower level first?

At what point would high nitrite crash a cycle?

Thanks!

 

[Retired Viking]

The thing with planted cycle is the plants do the heavy lifting when it comes to taking care of ammonia. The bacteria is only a secondary concern since the plants should absorb the majority if not all of the ammonia and eliminate in doing so the nitrates and nitrites. I would do a 50% water change.

 

[Fishy_Dan]

Thanks. I changed 50% of the water last night. Nitrite is now at 1.5ppm. Will change more water tomorrow to get it down further.

If ammonia stays at 0 next week and plants continue to fill out I'll start looking for those first fish!