I can't imagine how she has managed to keep her fish alive with ammonia at that level. You're fine adding her gravel and gunk, if she doesn't have disease in her tank.
As I have read in oodles of other threads, keep doing water changes, keeping nitrites and ammonia at .25 or less.
It's good that you are seeing nitrites, since that indicates the beneficial bacteria that breaks down ammonia is present.
Eventually the nitrites will be broken down by the nitrite loving bacteria that will develope and begin to flourish.
THEN.....:woot::dance:
The ammonia will be 0, nitrite 0, nitrates start to climb, which will feed your plants, YAY!! (keep nitrates at 20 or less by water changes)
You will then be ready to add a fishy or two.... I don't remember what size your tank is.... seem to remember that it is 10 gallon, right?
These guys can help with stocking suggestions. I heard that rummy nose tetras are great schooling fish and have a lot of nice movement in a tank.
But, I still consider my self a noobie compared to the fishkeepers here on the AC.
Hang on.... be patient... it's hard.... but you will get there.![]()