Level selling changes a little. Price ranges between 0.01 to 0.5 BTC per level. Minimal level to sell is 0.1. So the bonus won't be lower then 50% and bank will grow faster. I wish you all the best.
It is very good that at least half the deposit is used for bank but you could allow bonuses of less than 50% without taking more than 50% of a deposit to pay for the level sell, exemple : A sells for 70%, B deposit 1BTC and get 5/7 * 30% bonus, bank increases of 0.5
Next bank could arrive within a week
Play responsibly guys, this is a pyramid..