Also, there's no way that your actual flow rate is anywhere near 10 gpm. You'll have to do a bucket test, if you don't have a flow meter.
It looks to me like you could use a primer on the pressure that a pump provides.
Check out Dave Smith's article on amdmb.com .
Your rig is fine. The pump might be a little overkill, but the only way you could say for sure, would be by first measuring your water temp: normally, it should be 5 to 10 deg C above ambient (a thermometer somewhere in the room), but because you opted for a BIX, it might be a few degrees higher.
Now if your water temp is 80 to 90 deg F (27 to 32 deg C). then the issue is with your BIX, not the pump.
As for the dual pump, you ought to look at Bill's review of the Swiftech block, to see what performance you can expect at those flow rates, assuming once again, that you can take into account the pressure that the pumps can provide.