new member... sump questions

[hqgc]

Hello;
I am new to the forum and have been reading the forum for some time so I decided to register.
I am in the process of setting up a 150 gallon (aquagiant) with dual overflows and an aproxx. 50 gallon sump. Plumbing this tank turned out to be quite an affair. It all comes together in a package from china (or japan,not sure) with the plumbing included. The package came to be set up for inch and a half supply and one inch return. Turns out the grey pvc it came with was not your standard sizes. one inch (25 mm) was actually 28 mm and the inch and a half was the same conversion. Impossible to find fittings.
It did not come with enough of the bigger pvc so i decided to buy all new standard pvc from North America so I could Durso it.
Then came the next problem...... the holes it came drilled with were not big enough for the appropriate bulkheads. The one inch line was drilled out at an inch and three sixteenths and the inch and a half was drilled out at inch and 5/8 's.
the answer.. a silicone factory!
Anyways..... it is running and leak free. Now I am after suggestions for what to put in my sump. The tank will be a FOWLR predator tank.The sump has 4 small chambers starting at the supply and then one longer one where the pumps are. I am very interested in setting up a refugium but do not know if this sump is the right configuration.
Also been noticeing that the new trend is moving away from bio'balls.
Any suggestions would be great.
H.