Recently I have noticed a great increase in questions having to do media and which should be used in the askers particular situation. I thought I would put some effort into creating a "Guide" of sorts that may possibly be of some help to people with filter media questions, especially those who are somewhat new to the hobby or are just breaking into the DIY scene. I figured I would post many of the frequently used (or asked about) medias along with a few of the main upsides and downsides of said media. If anybody sees a commonly used media that I left out or just one that fits the guide feel free to add,although preferably in roughly the same format as to emphasize simplicity and improve the overall flow of the "Media Guide". with that said,let us begin with Sponges and Foams Japanese Mats: Surface area/cu.ft.:120 Upsides: A fairly easily obtained and inexpensive material suitable for both bio-media as well as a pre-filter media.Often available in bulk. Downsidesn the low side as far as surface area, compresses somewhat over time. Overall: Excellent choice for bio-media in a sump with no lack of space.I had mine stacked about 12" high and the compressed somewhat over about a years time...perhaps flipping them occasionally can prevent this. Filter Sponges/Foams Surface area/cu.ft.: roughly 75-175 depending on porousness Upsides: An excellent all around choice of media in most applications.Technically you could run sponges or foam of varying porousness in your entire sump.Holds up well under "Rinse and re-use" conditions. Downsides: Clogs.not the highest in terms of surface area.If you have a rather large bio-load or somewhat of a lack of space you may want to look into media with a higher surface area.Rather pricey if needed in large quantity as well, IMHO Overall:A good pre-filter or bio-media however frequent rinsing will be needed if you are using this as your primary source of mechanical filtration Natural Sponge Surface area/cu.ft.:100 Upsides:Rather inexpensive.descent micro-polisher. Downsides:Clogs easy.Not as porous as one would think,so water doesn't flow well through the center....although giving them a few good pokes with a kitchen knife works wonders.I am told they break down over time,although I have seen them successfully used in a sump for around 8 months. Overall:Not the best choice for either mechanical or biological but can be used until a better media is obtained. Plastic and Nylon Scrubbies/Strippers/Scourers Pot Scrubbies Surface area/cu.ft.:370 Upsides: Whats not to love?Fairly high surface area, clog resistance and an easily stackable shape make these an all time favorite for experienced aquarists everywhere.Not to mention they are cheap as hell. Downsides:If your bio-load is huge yet your sump is less than massive, you will still most likely eventually find yourself looking to add some media with a higher surface area. Overall:Best bang for your buck as far as bio-media Scour Pad Surface area/cu.ft.:150-200 Upsides:Excellent flow rate through media, among the best stacking medias in the "Guide" allow for maximum media coverage in tight spaces.Good as a "filler" media tucked here and there to fill in empty spaces in the sump. Downsides:Once again with a massive bio-load or very little space to work with you may find yourself wanting a smaller media with a higher surface area. Overall:Much the same as pot scubbies with some surface area sacrificed for far greater stackability. Floor Buffer Stripping Pads Surface area/cu.ft.:175-225 Upside:Good flow rate,stackable,fair surface area. Downsides:Same as scourers. Overall: Much the same as the scourers but usually tighter woven providing more surface area with a slight reduction in flow rate. Body Scrubbers Surface area/cu.ft.: 75 Upsides:free if you have a girlfriend (they always keep extra....) Downsides:Not pretty if your girlfriend ever finds out where her body scrubbers went.also they compress,have a low surface area and can sometimes contain perfumes built right into the plastic/nylon. Overall:Best used to soap up naked ladies. Flosses,Pads and Fibers Polyfiber Surface area/cu.ft.:? Upsides:Great mechanical filtration,extremely cheap when purchased in bulk.Can be rinsed and reused.Can also be purchased in pads.Cheap at the LFS and 5 times cheaper at a fabric store. Downsides:Clogs fairly quickly.Fibers can be (and often are) found tangled on your impellor or floating in your tank. Overall:The mechanical counterpart to pot scrubbies.Cheap,easy to maintain,and reusable. Filter Sock Surface area/cu.ft.:NA Upsides:Unless your tank is super messy you can often get away with having a filter sock or two as your sumps primary source of mechanical filtration,freeing up valuable space for more bio-media. Downsides:If your tank is super messy these will clog and mess with your flow rate somewhat. Overall:Not a bad addition to a sump with proper maintenance. Felt Surface area/cu.ft.: NA Upsides:Excellent for last stage mechanical filtration.Acts as a "micro polishing pad" for your sump. Downsides:Clogs extremely easy unless the water goes through several stages of mech filtration before going through the felt.Also the felt is often dyed (even the white felt is often dyed that color) so a bit of searching or a lot of rinsing is required. Overall:Often unnecessary yet hard to beat as a micro polisher for you tank. LFS Filter Pads Surface area/cu.ft. NA Upsides:Easily obtained,often best choice for mech filtration.Varying levels of porousness for further customization of mechanical filtration. Downsides:Somewhat pricey.Not often sold in what I would consider "bulk" Overallrobably the most frequently used mechanical medias available.Most often what people choose to put in their drip trays. Matala Fiber Pads Surface area/cu.ft.:60-175 Upsidesoes not compress.Good for use as a permanent mech filtration pad that can be rinsed and reused.Sold in bulk.Buoyant, otherwise much the same as a scouring pad such as scotch brite. Downsides:Expensive,Buoyant,Low surface area per cu.ft. means alot would be needed for bio. Overall:Basically a large scouring pad LFS Bio-Media Cannister Media Surface area/cu.ft.:ALOT (Varies) Upsides:most surface area in the smallest space possible is what cannister media is all about.If you have a very large bio-load than a sump full of pot scrubbies may not cut it,which is where the cannister bio-media comes in handy. Downsidesricey Overall:I'm sure it would be great if we all had the money to fill our sump with cannister bio-media like cell pore and the like but for those of us who don't defecate money I suggest just buying a container at a time and tossing it in your sump,eventually youll have quite a bit. My main chamber in my sump is filled with scrubbies however I toss in a container of cannister media whenever I have a few extra dollars (cell-pore,eheim pro,biomax,etc.) and I am slowly but surely filling my third chamber. Bio-Balls Surface area/cu.ft.:100-175 Upsides:fair surface area,shaped for maximum aeration,can be purchased in bulk,often for a fair price if shopped for online.One of the best things you can put in the wet/dry section of your sump. Downsides:can be pricey if your too lazy to shop around.I also hear Pot Scrubbies work at least as well as bio-balls in the wet/dry chamber,though I have not personally confirmed this.Effectiveness supposedly greatly diminished when submerged. Overall:The media most people use in the wet/dry section of their sumps, followed by scrubbies in a close second. Bio-Bale Surface area/cu.ft.:250 Upsides:Good surface area.Sold in Bulk. Downsides:Can become somewhat compressed over time, countered by the occasional "fluffing". Overall:Used much the same as you would pot scrubbies or bioballs, either in the wet/dry or fully submerged. Lava rock Surface area/cu.ft.:15-25 Upsides:very easily obtained and rather inexpensive.Good filler in a sump on a tank with a light bioload Downsides:Very low surface area really.If pores get clogged than you might as well just drop a stone in your tank for biomedia. Overall:Not the best choice for biomedia.Even If you were to keep the pores of the rock very clean your sump would still have to be about the same size as the tank your filtering.For those who still insist on using lava rock I might suggest breaking it up with a hammer and putting it in a media bag. Bio-Wheels Surface area/cu.ft.: ? Upsides:Supposedly house a super concentrated bacteria colony.Wet/Dry design. Downsides:Very high Evaporation.Somewhat of a price factor involved. Overall:Used with succes on smaller HOB's but not widely used in conjunction with sumps (unless you have a tidepool sump).Thought about adding one to my sump. Plants and Refugiums Upside:eat nitrates. Downside:Usually need special lighting.Not always room for a full size refugium,and often not enough space in your sump for a "mini-refugium" Overall:I fairly good idea.I want to put a refugium on my sump but have not decided how exactly to go about doing so. These are the primary choices for filter media that we as aquarists have available to us,and I hope this "Guide" is of some help to many an aquarist who are scratching their head,looking at that empty chamber on your filter and wondering what to place there.