Filtration flow rate for the 210 gallon.

Trying to make at least some basic progress on plumbing the 210 gallon. I'm a bit concerned that the flow rate for the sump filtration is going to be a bit on the low side.

I've got a Lifeguard Aquatics 5000 with a 1" MPT or a 3/4 barb. Head height is around 4.5 feet or less. http://www.lifegardaquatics.com/pdfs/q1aquariumDS.pdf
The tank was drilled for 3/4" return bulkhead. I need around 840 gallons per hour. http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

So plumb it up with schedule 40 as is with the 3/4" or make an attempt to drill for a 1 inch or 1.25 inch bulk head? The drain is 1.5" and I mostly have that part done except for a cut or two and the gluing part.
 
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