before it was that we need to hold a bitcoin in a certain address
I don't know how up to date you are with the current rules for the airdrop. Have a look at Tony's message below. He explains everything in there. There's no airdrop in October, but from November onwards it's back to normal I think.
The 10th round will be on the Full Moon of November (November 4, 2017 at 05:23 UTC), and the rules stay the same:
BTC to bytes: 1 BTC of proven balance gives you 6.25 MB (0.00625 GB)
BTC to blackbytes: 1 BTC of proven balance gives you 2.1111 * 6.25 million blackbytes (money supply of blackbytes is 2.1111 times more than that of bytes)
Bytes to bytes: 1 byte on any Byteball address gives you 0.1 new bytes
Bytes to blackbytes: 1 byte on linked Byteball address gives you 0.21111 blackbytes
Putting this another way, to receive 1 GB from the distribution, you need to already hold 160 BTC or 10 GB. These same holdings also give you 2.1111 GBB (giga-blackbyte).