Originally Posted by pookie2
Many thanks for this, should she keep dosing with ammonia?
No. There is no need. She has the tank cycled if the ammonia levels are going back to 0 after 24 hours. When fish are added they will be the ammonia source with their wastes. This keeps the nitrate cycle going as long as you have them in your tank. You're going to want to reduce your nitrates before you put them in however. You can do this with a series of water changes.
If your nitrate is at 80ppm and you do a 50% water change they'll go down to 40ppm, another 50% and you'll have 20ppm. And so on and so on. You'll want to get your nitrates as low as possible. I'd wait until around 10ppm to add fish but research beforehand as some fish have different levels of nitrate tolerance.
Keep in mind that after you add the fish they will contribute ammonia, which turns to nitrate, then to nitrates. You'll need to do water changes every couple weeks to keep them low.
Other options to keep nitrates low are skimmers, refugiums, and aquatic plants such as macro algaes but with the size of your aquarium it's really not necessary. Regular water changes will suffice in removing your nitrates and replenishing your nutrients.
After you get your nitrates down, I would do a 5G water change every week to two weeks. Monitor your nitrates and you'll get a feel for how often you should be doing water changes based on your bioload.