Using the other filter to help your new one is an excellent idea. Once the new filter is dealing successfully with the tanks natural ammonia supply, any excess good bacteria will die off. It may not be able to immediately deal with the nitrite (not that it absolutely must, mind you, the fish can tolerate small quantities for short times). I'd take twice daily nitrite measurements after a water change to see how long it is taking, and after the filter is well established, the results would be more accurate for the long term.
My tap water shows nitrites ???
- Thread starter cactusgal
- Start date
Sorry, no offense intended in any direction. RO units are a little more involved than just picking one up. Ammonia in the tap might be a good enough reason to get one, not for the tank but for you. They are costly with regards to filter replacement and installation though. Good luck with the fry. Keeping them in a cycling tank has got to be a bit of a challenge.
