Finishing a fishless cycle.

[Galoka]

Hi, again, been lurking, but things ahev been going fien with the tank so far.

Feel this post ought to be uneccesary given all that is out there, but reading up stuff just seems to confuse things more for me.

So 60L, Juwel Rekord 70 tank. 2nd hand, but with new filter media, gravel etc. No plants, but a bubbling driver with treasure chest (6yo daughter....) Nothing added to the water at setup except some dechlorinator. API Tap Water Conditioner. Temp 29C. Testing has been done with an API liquid test kit. Tap water is very hard, about pH 8.2 with about 20 ppm Nitrates (that was an intial test, I've not redone it yet, but will do). Water is clear, with no visible algae growing

To summarise, the tank was setup and left to settle for a few days, and started fishless cycling with added Ammonia on 13/9/11 - aming for a level of 3ppm (very oocasionaly added a few flakes of fish food). All has gone pretty much as expected, it pottered alongby the 29/9 Nitrites had risen upto at least 5ppm, and have continued, whilst Ammonia has been dropping down to 0.25ppm in about 12 hours, and has been redosed 2xday. Nitrates

By 4/10 Nitrates were up to 80ppm, Nitrites seemed to be dropping, but it's ahrd to always be sure at the higher levels with the API tests. But on 5/10 Both Ammonia and Nitrites first reached 0 ppm Nitrates higher, maybe 160 ppm on the test.

Evening of 6/10 Ammonia and Nitrites again at 0 ppm, Nitrates levles are dropping (undecided, between 40 or 80 ppm on the test).

So, I'm happy with all that - we seem to be approaching the end point, but not really sure on what to do (if anything) to 'end ' it. Keep on adding the ammonia and watching the Nitrites/Nitrates obviously. I get the impression that I'm aiming to get the nitrates down to atleast 40 ppm? Water change, or leave things be and let things continue to sort themsleves out (my gut feeling at the moment? Assuming that Ammonia and Nitires stay down at 0 ppm after about 12 hours from ammonia dosing, how long to continue to run it before we can delcare it 'done'?

(BTW - what happens to the nitrates produced at the end of all this. It's doesn't just go up and up? Presumably they are being used up by Alage in the tank?)