Bulk Reef Supply

BRS Felt Filter Sock with Plastic Ring

Grouped product items
BRS Felt Filter Sock with Plastic Ring 4” x 8”

SKU: 205905

In stock


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BRS Felt Filter Sock with Plastic Ring 4” x 14”

SKU: 205901

In stock


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BRS Felt Filter Sock with Plastic Ring 7” x 16”

SKU: 205903

In stock


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Why does BRS recommend this?

Felt filter socks give the best qualities of trapping free floating debris to give your tanks water that crystal clear appearance.  Felt filter socks with the plastic rings make replacement quick and easy, and most sumps will readily accept the BRS felt filter sock.  In most cases we will always put felt filter socks in our sumps.

Filter Socks are used on overflows to remove small floating particles from aquarium water. This can dramatically improve water quality and reduce maintenance on filters that would otherwise become clogged.


Felt Filter Sock is better at removing particles than mesh but can clog faster. The plastic ring fits common sump holders.

200 Micron Filter Sock

Filter socks come in mesh or felt and with a plastic ring or drawstring.


  • Mesh: Thin, doesn't clog as easily as felt
  • Felt: Thicker, better at removing particles, but can clog faster
  • Plastic Ring: attaches via ring that fits common sump holders
  • Draw String: attaches directly to plumbing
  • BRS recommends starting with felt socks and switching to mesh if they clog faster than desired.


Filter sock benefits:


  • Regular use will result in crystal clear water most convenient form of mechanical filtration.
  • Remove excess food, detritus, organic waste, dust and other particulates
  • A convenient form of mechanical filtration
  • Prevents larger objects like sand, crabs, and snails from damaging pump motors
  • Reduces ammonia and nitrate producing organic waste
  • Increases filter life
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Product Questions

Is the felt made out of polyester or polypropylene?
Question by: David on Feb 15, 2023, 11:31 AM
This is made from Polyethylene Terephthalate
Answer by: William Reed (BRS Staff) on Mar 23, 2023, 8:34 AM
Will these fit the Sapphire 34?
Question by: David on Nov 18, 2021, 9:19 PM
Yes, they will but the trigger hole has a slight oval shape to it, so you do have to squeeze the sock a bit.
Answer by: Matt Lucero (BRS Staff) on Nov 27, 2021, 1:08 PM
Which size will fit trigger systems 18c?
Question by: Andrew on May 4, 2020, 11:12 PM
Hi Andrew,

The Trigger 1 cube sump can use either the 4x8 or the 4x14 socks. The 4x14 may hit the bottom of the sump when installed but this should not be an issue once water is flowing through it.

Happy Reefing!
Answer by: Nick on May 13, 2020, 3:40 PM
Where are these socks made?
Question by: Ray on Nov 29, 2019, 11:48 AM
Hey there,
Thank you for reaching out with your question.
Our BRS filter socks are made in the USA.
Let us know if you have any other questions!
Answer by: William Glenn on Nov 29, 2019, 12:05 PM
Will these work in the Emerald 34 sump?
Question by: Diane Gergely on May 13, 2017, 12:39 PM
Hey there,
The BRS filter socks with plastic rings work great in the Trigger sumps. Many of us here at the office use them for just that!

Happy reefing!
Answer by: Zack on May 15, 2017, 4:20 PM
I recently bought the Trigger Systems Emerald 34 Sump and it came with the 4 x 14 felt filter socks which seem to be a bit long. When I did purchase the sump I ordered the two 4 X 8 felt filter socks and I think these fit much better. I just measured the sump and from bottom to the plastic ring is about 11 inches on these sumps. I might of course answered my own question about which length would be better. Per your advice on the video I will be buying more of the 4 X 8 felt socks so that I can be a better fish father and keep my tank cleaner. ;-)
Question by: jeffrey castor on Jan 25, 2017, 6:06 AM
Great question! If only they came in a 10" length! :-) I have the same problem with my Trigger sump, but I've opted for multiple 4"x8" socks and swap them more frequently. :-)
Answer by: Randy on Jan 28, 2017, 10:21 AM
I have ordered about 6 of these for my sump they work great except they never seem to completely seal in the opening.
Is there any O ring I can use or, can I put a heavy rock in the bottom of the sock to hold them tighter to the opening?
Question by: John Howe on Jan 21, 2017, 10:13 AM
Hey there, great question! Unfortunately there is not an o-ring or seal available specifically for that problem, but you have a great solution in weighing it down with a rock. I've actually done the same with one of my old systems! :-)
Answer by: Randy on Jan 25, 2017, 3:39 PM
Are these polypropylene or polyester?
Question by: Kevin Vinal on Nov 24, 2016, 5:50 PM
Great question! The rings are polypropylene and the socks are felt. :-)
Answer by: Randy on Nov 25, 2016, 7:30 AM
Is it acceptable/advisable to put bio-media in the socks such as Seachem Matrix or Brightwell Aquatics xPort Bio?
Question by: John Hildebrant on Jul 10, 2016, 11:07 AM
Hi John,
You can put any type of media you choose into the filter socks, however for a media sock, we would suggest using the mesh socks over the felt, since little particles of media, like getting stuck in the felt socks and become a bit harder to clean over time. The mesh socks handle loose media much better while allowing for more flow through them. The felt socks are best for water polishing.
Answer by: Charlie on Jul 11, 2016, 11:19 AM
I have a Precision Marine Sump 48 Pro which is labeled to have 7" holes for the Filter socks. Does that mean I purchase the 7" x 14" socks?
Question by: Jason Randall on May 5, 2016, 9:05 AM
I have a synergy reef systems sump. The exact same type as the one you guys have on the BRS160 video series. Just wondering what size you would recommend. I was thinking the 4x8
Question by: Alex on Apr 27, 2016, 4:58 PM
Great question!
The 4x 8 will work great additionally we have used the 4x14's as well which allow for a little more time before changing.
Answer by: Connor on Apr 27, 2016, 5:29 PM
Would the 4" be compatible as replacements for the socks that come with the CADLights SAIO series?
Question by: Lauren on Mar 7, 2016, 7:53 AM
Great question,
We are not familiar with the CAD lights sock size. As long as the hole for the filter socks is 4" exactly our filter socks will work great! Feel free to let us know if you have any further questions!
Answer by: Connor on Mar 9, 2016, 6:25 PM
Hello would this fit the reefer 250? Tried other 4 inch ring but no luck so far.
Question by: Carlos on Feb 4, 2016, 12:29 PM
Great question!
This will not work in the red sea reefer tanks unfortunately. The only socks we are aware of the if the socks directly from Red Sea. Feel free to let us know if you have any further questions!
Answer by: Connor on Feb 4, 2016, 3:08 PM
What is the inside diameter of the plastic ring for each of the sock sizes?
Question by: Mark Brown on Jan 18, 2016, 8:37 PM
Great question!
These filter socks have a lip which makes the inside diameter not very important for measurement. These will fit inside of a 4" diameter hole perfectly however! Feel free to let us know if you have any further questions!
Answer by: Connor on Jan 26, 2016, 7:36 PM
What is the correct size for a aqueon #1 sump?
Question by: jason on Jun 13, 2014, 3:51 AM
Hi Jason,
Either of the 4" filter socks will do the trick. I personally prefer to use the 14" even if its a bit long.
Answer by: Bulk Reef Supply on Jun 13, 2014, 3:51 AM

I've been using the 8" socks with good results - their also very durable and machine wash well.

1) Is using bleach necessary when machine washing?

2) What's the best way to tell when these socks need to be replaced (because of age/wear and no longer effective)?

3) If I wait too long will that contribute to an increase in nitrates?


Question by: Larry on Jun 12, 2014, 5:31 AM
Hi Larry,
1) It isn't necessary (many people just use straight water) but bleach does a very good job of breaking down organics.
2)If they have holes worn thru them or if the stitching starts to come apart would be when I would start to worry about them :-)
3)If you leave them in the tank to long it won't be as effective. It is more of an opportunity cost, by leaving the sock in for too long you give a chance for detritus to contribute to the nutrients in the tank, whereas if you had changed it out you would have removed it from the tank before giving it the opportunity. In the end, there won't be any more nitrates then could have existed without it, but you missed your chance to prevent them if you don't change them.
Answer by: Bulk Reef Supply on Jun 12, 2014, 5:31 AM
I use the felt sock with the plastic ring and would like to know how people clean them.
Question by: Ken on Jun 3, 2014, 7:03 PM
Hey Ken,
Some folks just throw them in the washing machine when they collect enough dirty ones. Personally I turn them inside out and give them a good rinse and scrub by hand.
Answer by: Bulk Reef Supply on Jun 3, 2014, 7:03 PM
I'm looking for a filter sock for my aqueon sump
Question by: Hank on Jan 26, 2014, 10:06 AM
Hi Hank,
This will be the 4x14 models with the plastic rings :-)
Answer by: Bulk Reef Supply on Jan 26, 2014, 10:06 AM
How often do you normally recommend you change the filter socks? what is the best method to clean the socks? if soaking - in what solution?
Question by: Don on Nov 19, 2013, 5:11 AM
Hey Don,
The more often you change them the better, that way you can remove the solids before they continue to break down and add additional nutrients to your water column. You want to avoid soaps when cleaning them but its pretty common for people to use unscented household bleach in water. Be sure to rinse them and all them to dry completely.
Answer by: Bulk Reef Supply on Nov 19, 2013, 5:11 AM
What is the micron rating for these socks? Thanks
Question by: David on Sep 4, 2013, 8:35 AM
Hey David,
Good question. All of our filter socks are 200 micron filter socks!
Answer by: Bulk Reef Supply on Sep 4, 2013, 8:35 AM