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High Flow Flexible Filter Media Cup - 4 inch - Sea Foam White


Item #: 6V3465

In Stock

High Flow Flexible Filter Media Cup 4 inch - Sea Foam White (Now Flexible & Slotted for Higher Flow)

Our 4" Filter Media Cup will replace all those filter socks you have hanging around. Made out of a BPA free Polypropylene, this 4" Filter Media Cup is a solid one-piece design, that holds any filter media. The opaque color will easily hide any blemishes that may occur from changing out filter media.

The round design allows the Cup to slide into place, regardless of which “side “slides in first. The cup fits most round filter sock holders intended for use with 4" diameter filter socks. An optional Filter Media Cup Adapter is available to accommodate C shaped filter sock holders or those with slightly larger diameter holders.

Simply drop the Filter Media Cup into your sock holder or filter tray, and fill with desired filter media. The beauty of the cup is you can use a wide variety of media types including filter pads, filter floss, carbon, GFO and biological filter media. To clean just replace your filter media as needed. You will no longer need to rinse and house used filter socks.

To reduce any noise produced by your Filter Media Cup, check out our reef-safe Filter Media Cup Silencer.


  • Dimensions: 6" Height and 4" Diameter
  • Color: Sea Foam White
  • Made in the USA
  • Material: 100% Virgin BPA free Polypropylene (typically used in Tupperware)

Note: GFO, Carbon, and other chemical filter media should be placed inside a media bag to prevent media from exiting the filter cup. Our Filter Media Cups are designed to fit sumps that use standard 4" filter socks; However, they will not fit Trigger Systems Sumps with an oval-shaped sock holder. As a precaution, we do recommend a thorough rinse with vinegar and water before placing into your filtration system.

Manufacturer information

If you`ve ever used filter media inside a filter sock you know how water tends to bypass filtration materials like activated carbon and GFO. Maybe you`ve even given up using filter socks, leaving your filter frame unused. Why not switch to the Filter Media Cup instead?

The cup is designed to drop into a filter sock holder. The bottom of the cup has large holes so water flows freely through the media. The media cup works like a mini reactor.

There are several ways to use the media cup. You can fill it with bagged filter media, like activated carbon. It`s possible to use several types of bagged media, like GFO and resins at the same time. Putting a layer of filter floss or sponge on top of the media helps to evenly disperse the water and prevent channeling. Biological media works too.

We really like how easy it is to rinse fresh filter media, like activated carbon or resins. Just place the loaded filter cup under running water. Your hands stay clean and the media is washed and ready to use.

The filter cup is injection-molded in the US using food-grade, BPA-free polypropylene plastic, so no worries about being reef-safe. Give the cup a quick rinse with vinegar to remove any traces of mold release before use. An optional Filter Media Cup Adapter is available to accommodate C shaped filter sock frames or those with slightly larger diameter holders.

This Filter Media Cup opens up new opportunities to enhance your filtration system. You can even switch back and forth between a micron filter sock and specialized filter media for the best of both worlds. The cup and adapter ring fits most sock holders. If your curious if it will fit your sump, contact us and we`ll be happy to check!

4 Stars


Reviewed on
January 22, 2021

Yes, I would recommend this.

Work as designed - no more filter socks to clean

Pros: Inexpensive and flexible

Cons: Not see through

Works as designed. I have a trigger 39 sump and order three of these with the extension rings, a quick mod on the extension ring and was able to place 3 of these cups in place of filter sock. I use filter fiber in the cups and replace the filter fiber every 3-4 days.

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Reviewed on
September 03, 2019

No, I would not recommend this.

They don’t fit. Rim needs to be bigger.

Pros: Durable plastic

Cons: Do not fit

Bought these for my Synergy Reef sump. Figured I’d give them a try when my filter socks are washing. Well, they don’t fit. I have 4” sock holes and there’s a small gap where the water runs right out and it’s loud. You would think that they would fit any standard 4” filter sock hole, but apparently not all 4” sock holes are the same. BTW the spacers don’t work either. Maybe it’s just Synergy Reef sumps.?? So now I’m stuck with these cups, and I’m gonna have to DIY a thin acrylic ring to go under the rim of these cups so that they will seat right in the sock holes. My suggestion if you want to buy this product is...make sure you measure down to 1/16” to know for sure if they’ll fit.

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Reviewed on
July 13, 2019

No, I would not recommend this.

Won't work for me.

Pros: Good idea, lousy execution

Cons: Don't fit the standard 4" holes in my Trigger sump

I ordered these to switch from filter socks to using Poly Fil. I have a standard Trigger sump with 4" holes for filter socks and these fall right through the hole. I measured them and they are only 3 13/16" to the out side of the flange?!

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Reviewed on
April 02, 2019

Yes, I would recommend this.

Great upgrade to the regular filter cups.

These are a great upgrade to the original filter cups. Doesn’t back up the water like the first generation cups.

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