Nice tank.
I've had a 7 gallon bowfront set up for about 3 months now. Mostly low light stuff and a royal gramma.
Aquaclear 500 !!!! :shock:
I'm only using a aquaclear mini on mine. You must have the flow turned down low or it would be like a washing machine in there.
That's a great idea to use the 500 as a refugium. It's big enough that it adds to the total water volume.
What lighting are you using over yours for the clam?