First you need to determine the maximum flow rate of your returns... then to be safe I would stay at least 15% lower than their maximum.
You could connect the sump's return pump to also power the UGJ... but personally I would run them on separate pumps. This will increase the overall current in the tank working against dead spots and/or debris from collecting in certain areas (although to a degree this will always happen). Running them separate will also prevent an imperfection in one system from effecting the entire tanks filtration.
I also confess that I use heavy filtration...
You could connect the sump's return pump to also power the UGJ... but personally I would run them on separate pumps. This will increase the overall current in the tank working against dead spots and/or debris from collecting in certain areas (although to a degree this will always happen). Running them separate will also prevent an imperfection in one system from effecting the entire tanks filtration.
I also confess that I use heavy filtration...
