Use a Pot Scrubber / Sponge In the Fluval Spec Aquarium Filter

I was kicking around ways to substitute improved filter media into my Fluval Spec V and found some people in forums suggesting common materials to substitute. Among them were nylon pot scrubbers, scotch-brite pads (dollar store scrubbie pads), filter wool, polyester fill (polyfill – found at craft or fabric stores for pillow batting). That got me to thinking and I checked out what was available at the dollar store.

I found a great little combination scrubber and sponge in the cleaning section.

dollar store pot scrubber sponge for aquarium filter

It has a flat pot scrubber on one side, similar to a scotch-brite pad. The other side is a fine sponge. I bought the package of two for about $1.16 USD.

pot scrubber with foam sponge for use in DIY aquarium filter

pot scrubber with foam sponge cut to size in aquarium filter

How to Use in a Fluval Spec Aquarium

The length of the sponge fits perfectly inside the filter section of the Fluval Spec Aquarium; I just needed to trim the width down to about 2-1/2″ (64 mm). A set of kitchen shears made quick work getting it down to size.

I was a little leary about this cheap sponge having some chemicals in/on it, so I rinsed heavily in tap water, then I let it soak for an hour in dechlorinated tap water in a small tupperware container.

pot scrubber with foam sponge as added filter in Fluval Spec aquarium

After it was thorougally rinsed and cleaned, I wedged the sponge/scrubber above the Fluval filter and below the removal handle. It just barely fit below the handle. I considered cutting the plastic handle off but it’s actually nice having that to remove the filter media. I mounted the sponge with the scrubber side up. It is more coarse and will catch the big stuff first, leaving the finer sponge second. This add-on filter media works well at the top since you can remove it and clean it separately without disturbing the main components of the Fluval filter.

How well does the scrubber/sponge combo work?

I like how it has performed in my little nano aquarium. The stock filter material in the Fluval Spec is allright, but the sponge filter that serves as mechanical filtration is a bit coarse and the large holes allow too much detritus through the tank. That is where this added sponge filter on top helps a bunch. I cut it so that it fits very tight and not much water bypasses around it. The water flowing first through the coarse pot scrubbing section and then through the finer sponge really knocks down the particles floating around the tank.

pot scrubber with foam sponge in Fluval Spec V Aquarium

I think the price is very good. Each sponge will cost about $0.50 each and I anticipate they will last a few months. They will essentially be throw-away media that will protect the Fluval filter sponge and hopefully keep it cleaner. As part of my weekly maintenance, I will just squeeze out this sponge on top to get the big stuff out.

The only odd part of this configuration is that water can bypass the top scrubber section when it enters striaght through the return slots. I don’t think it’s a big deal. With the way it fits so well in the filter section, all the water has to pass through some part of this sponge and it does a great job of clarifying the water.

pot scrubber with foam sponge in filter section of Fluval Spec Aquarium

The filtration components for this Spec V are really coming together. I am currently running: DIY dollar store scrubber/sponge, stock Fluval sponge filter, Fluval Biomax (in the upper section of sponge filter), and Seachem Purigen 100ml Bag (in lower section of sponge filter). Deciding to not use the stock activated carbon bag and instead use the purigen helped make the water clearer, but I think this little sponge filter has helped just as much.

A Word of Warning for DIY Filter Materials:

One thing to consider when sourcing filter materials that are not specifically made for aquariums: You are taking a bit of a risk that the sponge, pot scrubber, poly-fill, or other material you are using may have chemicals that are not friendly to aquariums. I took the risk and it worked out fine. All my fish and shrimp are perfectly healty. Do as I did and make sure and rinse anyting out througally. Avoid cleaning products that say “antibacterial” as they surely have chemicals that are bad for your tank inhabitants. Once you find a source for material that is proven clean and healthy, don’t change! Keep using the same product and be on the lookout for changes in packaging that may indicate a change in the product.

There are some good, and safe, filter materials available online.

Update: Aquarium Specific Products are Better:

Since I wrote this article, I have discovered a few aquarium specific products that are available that not only outperform the pot scrubber filter I wrote about here, but they are actually cheaper too!

I have a full writeup here.  They are a two stage system with the first being a  Bonded Blue & White Poly Filter Floss Pad and the second a 100 Micron Polishing Filter Pad.  Not only is this system much more effective than my homemade solution here, it is actually cheaper (if you replace it regularly) – a pair of each cut to size for a Spec aquarium cost about $0.38 USD each.

poly filter floss and polishing pad aquarium filter media

Homemade solutions still may make sense for those who don’t have access to specialized bulk aquarium filter media like these.

12 thoughts on “Use a Pot Scrubber / Sponge In the Fluval Spec Aquarium Filter

  1. Just bought a Spec V. I love your blog. It’s made it easy finding out what i need to make my tank better!

    1. Glad you found the site and that it helped – Have fun with your Spec V!

  2. Hi, I built a 4 shelf media rack for my Fluval Spec 3 and was wondering if another shelf to make 5 shelves would be too much filtration cause there’s enough room to put another shelf, I am currently running 2 ceramic bio media pouches, course filter foam and polyester filter floss on the top. I’ve discarded using the carbon and plan to put another another ceramic media pouch on the 5 shelf if possible.

    1. Sounds like a neat design! Not sure if you need any more ceramic media – more isn’t always better. How about another type of filter media like purigen?

  3. What a great idea to increase filtration capacity in a small tank. Thanks for the tip on making sure whatever media you purchase is aquarium safe. Great pics Nate thanks.

  4. All your articles are very detailed and helpful. I just got a Fluval Spec V and appreciate all your guidance. Looked at many options to protect my future betta from strong flow into the filter area, and the sponge you show here was pure genius.

  5. Hi Nate, Love your tips and ideas for the Spev V Tank, thought i’d share mine with you.

    I have blocked the small slit using a small old suction cup.

    I have added a filter floss bio pad to the top of the sponge under the plastic handle. This is the Juwel bioPad in Small suited for the Bioflow Super and Compact Super tanks and this fits perfect with no cutting required and collects fine debris. People who think their filter isn’t doing much will soon see the amount that passes through the top grille daily with what the white pad collects.

    I have removed the carbon bag in the top and replaced with Purigen, also the stock large black sponge has plenty of room in the middle section which I thought was going to waste so I cut out a square hole the same size as the bottom hole and added a second bag of biomax to this.

    I have 8 Scarlet Badis in my tank with 4 Otocinclus Catfish and no problems whatsoever with filtration.

    Also it might be of interest to others with the original spec v tank led light unit wanting to upgrade to the new led light which is a million times better that the original that it is available now to buy separately. part code for this is A14689 and/or 015561346894 depending on websites.

    Currently looking into changing the output nozzle with one that has an adjustable venturi built in to give air bubbles to the tank.

    Just thought id share my ideas.

    Keep up the good work


    1. very good set of tips – thanks! I may need to get some of that filter floss to try out.

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