so 13 and 14 is good for large field in x-treme

No, 4-6 is. 13 and 14 are hit and miss.

ok thanks thats why did i dont get any

It also depends on the server. Are you in Speed?

oh yeah, how hard is it to get a big planet that is in slot 15?

They're fairly rare.

well ill keep trying->100CS later...YESSS!!

me im in x_treme

No way of "really" telling/scanning then right? Just pure chance? (Was wondering this myself before launching anymore colonies)
*BTW I'm concerned about speed & standard for the moment please, thank you.)

It is just chance, but the general experience of most people is that you have a better chance in slots 4-6 and 14. In Speed planet size is capped at 325 and I advise abandoning anything much smaller than that. In Standard I am not sure what the max size is (I think it may be 600) but you can certainly get 500+ fields there, which is totally unnecessary though. 300 fields in Standard is certainly sufficient.