The impact should be minimal as we already know that the ECB has made liquidity plentiful over the last few months
The range of estimates is somewhere between €10 billion to €200 billion, but in any case will fall well short of the €1.3 trillion allotted at the June tender. ING says that:
This time around banks have chosen to repay just shy of €11bn out of older tenders ahead of today's allotment. This low amount already ensures that the net impact on excess liquidity in the banking system will be largely neutral at worst.
Barclays expects the figure to be €10 billion, Commerzbank €60 billion, JP Morgan €50-100 billion, Danske €50-100 billion, and Natwest €200 billion.