Sorry I meant to post that.
10 Gallon tank (18 x 12 x 10)
Everything in the tank (including the tank) was bought new
and I used fresh tap water with a bit of dechlorinator in
it. There was 8 fish in it for two days (thanks to the pet
shop man), but after that there have only been 4 platties
My 40x15x18 cycled in 14 days from adding fish, but my new 10 gallon is in the process of maturing, added fish on sunday, and the NitrIte level has peaked and is now dropping, so it could be on course for just over a week - although I cheated a bit and added a couple of pints of water from the main tank...
Did I forget to mention I had bought another tank - manged to persuade my wife easy because she didn't like the idea of the fry getting eaten