No, I do not mean the minimum balance to avoid paying account monthly fee.
I need to know when I am not in Hong Kong for a few years, I need to keep the accounts active to avoid these account to put into inactive. This happened to my accounts before, and I have to process setting up new account and take time to transfer the money over to the new account. And hassle to setting up all the auto-pay again from the new accounts.
I know I need to perform transaction, such as deposit some amount of money into these account to keep these account as "active". What is the right kind of minimum amount?