7.1. Review of Media

The first consideration when choosing a filter media is the ammonia oxidizing capability of the media.

Filter Media Ammonia Oxidizing Capacity

Three tests (24 ninety day runs total) of the ammonia oxidizing capability of various filter media were run. All three tests correlated remarkably well. The tests gave an “efficiency” number for various aquarium filter media.

The first number, the “efficiency from two tests” is the average ammonia oxidizing that 15 cubic inches (245,81 cm³) of media accomplished over a 90-day period. The second number is the “effective” surface area in square feet per cubic feet calculated from that test. The third number is the effective surface area in square feet per cubic feet calculated by simple mathematics. The correlation between the test results and the calculated surface area is very significant and means the testing was accurate.

Media	“Efficiency” from two tests *	“Effective” surface area ft²/ft³	ft²/ft³ from math	“Effective” surface area m²/m³	m²/m³ from math
Fluidized K1 media	not tested	600	na	1980	na
30 PPI foam	17	340	400	1122	1320
Pot scrubbers	14	280	80	924	264
Static K1 media	13	260	200	858	660
20 PPI foam	not tested	220	180	726	594
Aquarium gravel	6	120	120	396	396
Blue Matala pads	5	100	120	330	396
Eshoppe bioballs	5	100	60	330	198
¼ to ½ inch lava rocks	3	60	60	198	198
Matrix	3	60	30	198	99
Biohome ultimate	2	40	30	132	99
Ceramic rings	2	40	40	132	132
* average ammonia oxidizing that 15 cubic inches (245,81 cm³) of media accomplished over a 90-day period

The higher the number the better the media. So foam is the best static media and ceramic rings are the worst media for canisters by this test and by math calculations. Since foam must be exactly cut to the proper size to prevent flow around pot scrubbers and K1 are much easier to use successfully.

Note that for the metric system simply multiply any of the square feet per cubic feet numbers by 3.3 to get square meters per cubic meters. For the metric system 100,000 f²/f³ thus equals 330,000 m/m³ or 330 m²/liter .

These numbers reflect a canister which will give a hobbyist crystal clear, bacteria free water which in turn will give one very healthy fish. These are some huge differences.

Click on this link for the test:

7.1.3. Filter Media Test

Surface Area Calculations

Note that the “surface area foot² per foot³” is generally based on simple math, not on the claims of the manufacturers. The calculations are:

Biomedia	Diameter of pore in inches	X= Surface area of a sphere in inches²	Y= pores per inch²	XxY=Z	Zx12= surface area foot² per foot³	Effective surface area
60 ppi foam	0.016	0.0008	216	173	2076	800
40 ppi foam	0.025	0.0018	64	115	1380	500
30 ppi foam	0.033	0.0036	26	97	1164	400
1/8 inch gravel	0.125	0.048	512	24	288	140
3/16 inch gravel	0.188	0.111	149	16.5	198	100
3/8 inch gravel	0.375	0.444	19	8.45	101	50
1/2 inch gravel	0.5	0.785	8	6	36	20

Calculating surface area of filter media

The reduction of the figures in the final column reflect the realities of the situation. For instance, only about 40% of the foam cell is surface, 60% of the cell area is void, which allows great water flow but doesn’t give surface area.

These math calculations were tested and the tests generally followed the results of the math. The only significant inaccuracy was that pot scrubbers were much better than math calculations predicted.

Because of reticulation, flow and free volume considerations the surface area calculations and chart above can be superseded. Extrapolating from the testing and giving aquarium gravel the most dependable surface area calculation, gives the following “effective surface area” by media. This is the surface area which should be used for calculating the required volume of filter media for a given weight of fish.

Biomedia	“Effective” surface area ft²/ft³	“Effective” surface area m²/m³	ft³ to get 5ft²	m³ to get 0.46m²	ft³ to get 100ft²	m³ to get 9.29m²
Fluidized K1 media (60% loading in sump)	540	1782	16	0.45	320	9.06
30 PPI foam in canister or sump	340	1122	25	0.71	500	14.16
30 PPI foam powerhead operated sponge	340	1122	25	0.71	500	14.16
30 PPI foam air operated sponge	300	990	29		580
Plastic pot scrubbers	280	924	31		620
Static K1 media	260	858	33		660
20 PPI foam in canister or sump	260	858	33		660
20 PPI foam powerhead operated sponge	260	858	33		660
20 PPI foam air operated sponge	230	759	38		751
Powerhead operated undergravel filter	140	462	62		1240
Aquarium gravel in canister or sump	140	462	62		1240
Air operated undergravel filter	120	396	72		1440
Blue Matala pads	120	396	72		1440
1/8 inch garden pumice or perlite	100	330	86		1720
Bio balls	100	330	86		1720
Alfagrog	80	264	108		2160
1/2 inch lava rock	60	198	144		2880
Seachem Matrix	60	198	144		2880
Biohome Ultimate	40	132	216		4320
Ceramic rings	40	132	216		4320
Ceramic balls	30	99	288	8.16	5760	163.11
Expanded clay pebbles	30	99	288		5760
Cubic inches to get 5ft² = (5/E.A.)x1,728 100ft²=(100/E.A.x1,728)

Note that for the metric system simply multiply any of the square feet per cubic feet numbers by 3.3 to get square meters per cubic meters. For the metric system 100,000 f²/f³ thus equals 330,000 m²/m³ or 330 m²/liter.

Ammonia Oxidation versus Water Clarity

What is often missed in these calculations is that it is easy to oxidize ammonia. Oxidizing ammonia only requires on the order of five square foot (0,46 m²) of surface area for one pound (454 gram) of fish per testing and per the literature. But testing and the literature support the fact that crystal clear water requires somewhere around 100 square foot (9,29 m²) of surface area per pound (454 gram) of fish. And crystal clear water is healthy, disease free water.

Manufacturers’ Claims and Instructions

The claims of many ceramic, pumice and sandstone media manufacturers are based on something called the BET nitrogen infusion method. It measures the amount of nitrogen which permeates a media and adsorbs onto the surface of the media in a single molecule layer.

Since the nitrogen molecule is a couple of billion times smaller than a beneficial bacteria cell this is obviously a very misleading statistic. If a beneficial bacterial cell can’t even get to a surface, let alone form a film on it, the surface is useless. The tiny pores in many media are thus simply of no use.

Another concept which is pushed by manufacturers of some filters is that media needs to be replaced on a regular basis. Some HOB manufacturers say their cartridges need to be replaced every month. There are canister filter manufacturers that say the ceramic bio-rings and the foam in their filters need to be replaced every six months.

This is just ridiculous. Pure and simple profit motivated Hogwash!!!! Cartridges are easily cleaned when they plug and can be reused for years. Foam will last five to ten years while ceramic or plastic media will last for twenty years or more.

Belief Perseverance Effect

Experience on social media has shown that the table above and the testing which produced it will not be believed by 90% of the hobbyists that read it. They will fiercely defend their favorite media (Matrix is probably the single most popular filter media and easily 90% of all biomedia used is either expensive Matrix, Biohome or a ceramic media) and no one will be able to change their minds.

If anything, heavy, slick marketing and the “power of popularity” will make them more intransigent. If presented with test data and logical, common-sense proofs of the data, they will rationalize the experiments away and then rationalize some more. This is called “belief perseverance effect,” something we all fall prey to, and there is no point in fighting it.

“Nothing dies harder than a lie that people want to believe”

Calvin

The numbers are accurate, and that fact is proven in the links below.

For more information about filter media click on these links:

7.1.1. Filter Media Costing

7.1.2. Function of Filter Media

7.1.3. Filter Media Testing

7.1.3.1. Filter Media Ammonia Oxidation Test

7.1.3.2. Filter Media Water Clarity Test