Mon-Thurs 7am-5pm PST
Fri 7am-4pm PST

Questions about products, orders, shipping?
Contact us by call or email

High Flow Flexible Filter Media Cup - 4 inch - Calypso Blue


Item #: 6V3441

In Stock

High Flow Flexible Filter Media Cup 4 inch - Calypso Blue (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: Calypso Blue
  • 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 30, 2021

Yes, I would recommend this.

Fits perfectly

Fits my 4inch sock holder perfectly and it matches the sump.

Was this review helpful? 0 0


Reviewed on
January 03, 2021

Yes, I would recommend this.

Great product

Pros: saves time. no more cleaning filter socks

Cons: None

Great idea to filter socks and the task of cleaning filter socks.

Was this review helpful? 1 0


Reviewed on
June 12, 2020

No, I would not recommend this.

much smaller than 4 inches

When I buy a 4" filter sock or holder, I expect it to measure 4" across...My holder does, my filter socks do and they work fine together. This measures right around three and three quarters inches, so it slips right through the 4" holder. I cut a gasket to correct the issue and can now use it. Would give a higher rating if the dimensions were given in the product description.

Was this review helpful? 0 0


Reviewed on
June 03, 2020

No, I would not recommend this.

Poor quality control, too small

Cons: Doesn't ft, can't use it in it's "out of the box" condition

Does not fit in my 4" holder that works just fine with 4" filter socks. Measured the diameter and it's a tiny bit under 3.75". A quarter of an inch too small makes a big difference. Cup appears to be sturdy enough, will have to find a way to shim it though, in order to use it.

Was this review helpful? 0 0


Reviewed on
January 07, 2020

Yes, I would recommend this.

No More Filter Socks

Pros: Great Alternative to Filter Socks

Cons: Doesn't hold as much Filter Media as Filter Sock would.

Don't waste money on replacing Filter Socks.

Was this review helpful? 0 0


Reviewed on
August 07, 2019

Yes, I would recommend this.

It fits

Pros: Solid

Cons: Non

It do what it does and it well built.

Was this review helpful? 0 0


Reviewed on
April 16, 2019

Yes, I would recommend this.


Pros: Filter cup fits my refugium


I was tired of changing the socks in my my Aqueon Proflex refugium so i decided to give the 4" filter cups a try. I order only 1 to make sure it fits. It fit perfectly!. I've filled it with media and so far good. The only reason i didn't give it 5 stars was the delivery sucks it took longer than the 7 days. My guess is ALL of Marine Depot's shipping crew was at REEFAPALOOZA ORLANDO and didn't get to my order until they returned. Overall im satisfied and have placed an order for anther cup.

Was this review helpful? 0 0

We use cookies to provide a personalized site experience. By continuing to use & browse this site, you agree to our Privacy Policy.