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What is the best filter media


19 Jul 2007
Lincoln UK
As per the title really.

I only have half my filter filled with media and this is because I want to keep the flow rate as high as possible.

With this in min, what options are there for a media with a high surface are that also doesn't reduce flow too much. I have read a fair few comment about sintered glass on here recently as not reducing the flow as much. Does it have a higher surface are than ceramic hoops or bio balls etc.



Expert/Global Moderator
11 Jul 2007
Chicago, USA
Hi Andy,
The Eheim Efisubstrat II seems to be one of the better options. When I first opened the package I though someone had pulled a joke on me because it looks like some kind of breakfast cereal. :wideyed: Reports indicate that this has a very high surface area per unit volume. None of us can actually measure the actual area and of course it's very difficult to compare different media. I believe also that because these are small spheres they allow sufficient space between each unit to minimize flow reduction, or at least to get a more or less even flow across the volume. The trick with these is to keep them from becoming clogged with detritus so mechanical filter media like the little cylinders should come before these. Barr advocates the use of zeolite and purigen as well as they react directly with ammonia. I use a combination of all these and have had good luck.



6 Jul 2007
Aston, Oxfordshire
Doesn't Eheim Efisubstrat II have nitrate reducing properties as well?

Its personal choice, but even in a heavily stocked tank, is there anything these special (and expensive I might add!) media do that good old sponges cant? Ok you might need to increase the amount of sponge by upgrading the filter, but in a planted tank you'd probably do this anyway. Also, the plants will do most of the filtering anyway.

Why spend the money on fancy media?


Ed Seeley

3 Jul 2007
I am pretty sure that Ehiem media is sintered glass!

Personally I use sintered glass in all my filters (it's me who keeps banging on about it! :rolleyes: ). It has a very high claimed surface area relative to the amount of media. Is personally prefer the cylinder formed media as it has a higher void rating per litre as long as you stack it randomly and don't arrange all the cylinder to lie across the basket!

IME I find foams are OK as a media once they have aged a bit and softened, but when new I really have doubts about the ability of a biofilm to develop and stay attached.

I was thinking that if I ever get to set up a giant tank or fish house (keep hoping and planning...) I would probably use a version of a modern koi filter which are designed to deal with very high waste levels often in heated ponds at near tropical temperatures. Wouldn't be much good for an ordinary planted tank as they use copious amounts of air to gas off ammonia and increase oxygentation and, in doing so, nitrification. The 'best' pond medias touted now are either K1 (a floating plastic also used in sewage treatment) or a baked cermaic media (used in trickle filters called showers). Again it is high relative surface area, differential flow rates and high void area that they have in common.

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