Well, its been a hard 3 weeks of testing, adding ammonia, but I THINK I'm nearly there.

I now add 5ml of ammonia each day and its always 0 the next day (120L tank)

Ive just took it back up to 5ppm at 2pm, gonna see how many hrs it actually takes to reach 0

NitrItes were about 40ppm last week, tested today and its on 0.25ppm

NitrAtes are off scale, but not worried about that, will do an 80% water change when nitrItes hit dead 0 (or is 0.25ppm acceptable now?)

Water is still crystal clear tho, although I have a EX700 filter.
Ive not done anything with the filter since I started, will the filter media still be OK?

Need to start deciding on fish now I guess, might get some Java plants tomorrow and put some food in the substrate (gravel).

Any tips etc now gratefully received on types of fish and how many I can have