网上申请citi EZ checking的开户$200bonus的条件中有

You must open and fund online a Regular Checking account in the Citibank EZ Checking pricing package and deposit at least $1,500 by 7/31/2006.

请问这$1500的要求是只要fund$1500还是要保持帐户中$1500的balance一定的时间。