Hook it all up and change the water frequently till the tank is cycled if u have fish in there. Use dechlor and match temp.
Calculate ur filtration needs by ur gph and volume to know ur appropriate turnover rate. A good baseline not considering stock is Atleast 5x turnover per hour, 8-10x is preferred with heavy stock. So 150 gals should have Atleast 5(turnover)x150gals=750 gallons per hour (gph), filters actual gph (filled with media) are usually half of what is says on the box, so general rule is it says its 400gph its prlly closer to 200gph so right now u have 400gph (realistically) imo u need 2x that for a cleaner enviroment. U could scrap it all and get a big sump filtration system so u don't have the clutter of multiple filters and wires. Or try fx5 or eheim 2262
The better the brand the more efficient the filters pump is (GENERALLY)
Go S. Vettel #1 rb8