pump size

I have just setup a red sea desktop peninsula however it appears that the overflow drain is not working correctly. It seems to be... Well... Overflowing. It is meant to drain into a little hole in the far right of the plastic overflow grating peice but just fills up too fast and overflows into...

Friends, I am trying to find a good return pump for my Redsea 625. I have a Syncra Silent 5.0 but was thinking about just using that for the chiller and use a DC pump. I was looking through the DC pumps and came across eflux. Anyone got any opinions on those? Or should I go with a Vectra S2 but...