Hey
@TheSheff, glad you’re enjoying your Main + Extension!
The EXT 200 is slightly above our general
150–180 gallon recommendation for a triple-M setup. Our usual recommendation, though, is to use
one M for each standard 4-inch filter sock position.
Since the stock sump has three filter sock positions,
one Main + two Extensions should work well for this setup. The M supports higher flow and provides more consistent filtration than traditional filter socks, so replacing all three socks with three M filters should comfortably handle the flow that those original socks were designed to accommodate.