Still Looking for the Volume Peak

When SPY gapped down on Friday it closed the gap at 105.85. I based the 104.58 low on the fact that SPY would drop to close the 105.85 gap and that 104.58 was the next support level below. Now it's not clear anymore that SPY will hit 104.58. Still, the volume has not peaked so I expect further downside in SPY. I am looking for volume in excess of 600M to signal the low.