Size 4 splits the difference: 4″ diameter like a size 3, but 14″ long with a pointed bottom — about 1 square foot of media and roughly 45 GPM capacity. It’s the step up when a small housing needs more dirt-holding capacity without jumping to the 7″ bag standard.
Size 4 Specifications
| Attribute | Detail |
|---|---|
| Diameter | 4″ |
| Length | 14″ |
| Surface area | ~1.0 ft² |
| Typical max flow | ~45 GPM (clean water; derate per the sizing guide) |
| Bottom style | Point (conical) |
| Media | Felt 1–200 µm, mesh 35–800 µm; FDA grades available |
| Construction | Sewn (welded available for specialty applications) |
| Top options | Steel, stainless, polypropylene or nylon ring; drawstring; open |
Fits
Size 4 bags fit standard #4 (4×14) housings across the major brands. The 4″ ring is shared with size 3 — a size 4 bag in a size 3 housing will bottom out in the basket, so measure the basket length if you’re unsure. Cross-referencing a brand part number? See the cross-reference guide.
Doubling Up Without Upsizing
A size 4 gives roughly double the area and capacity of a size 3 in the same 4″ format — the same relationship size 2 has to size 1. If your small housing takes the longer basket, it’s the cheapest capacity upgrade available.
Ordering size 4 bags? Call 800-554-8555 or request a quote.