The very purpose of good "noodles" is to own something so tough and hard that you may never have to replace it.
Members sometimes use the term "noodles" to describe small rings (they are also often just called "rings") that are made of non-shiny ceramic. Its usually white or tan colored and has a fine rough surface kind of like bricks in an oven where your fire clay pottery. The ceramic surface is designed to create the best sized and maximum surface area for holding the largest number of beneficial bacteria possible. These ceramics are among the best biological media possible but there is always competition from sponges, which are also excellent. The reason the ceramics are shaped into "rings" (or "noodles" as it were) is for another interesting reason: By letting the rings fall randomly into their compartment in the enclosed filter case, they form a filter layer that will "randomize" the small water pathways. In filters you do not want a "path of least resistance" to happen. Its important for the rings to be heavy enough not to shift in the water flow (thats why they are thick) and for them to be poured in in a random way so that they will assume different angles of repose in the layer.
Often the "ring" layer is the first biological layer right after the most coarse sponge. This randomizes and slows the water flow right away, which is a good thing. One of the reasons large cannister filters are so good is because of these big layers of media causing a slower movement during the filtration stages. Often the next layer is composed of ceramic "pebbles", which are rough rock shaped pebbles, larger than gravel usually. They are composed of the same ceramic as the rings and have the same type surface. The idea here, I believe, is to close down the little water streams and force them through even smaller spaces so that even smaller debris will be caught, mechanically, and there will be even more exposure to the vast surface area of beneficlal bacteria. Often the pebble layer is followed by an even more fine-pored sponge to further clean the water mechanically and biologically. If there is filter floss it is usually last in the pathway of the water. Filter floss can really get the small stuff out and make the water sparkle more but it requires frequent changeouts and many think its more trouble than its worth, but that depends on your current goals.
There are many brands of these things: Eheim make Ehfi Substrat Pro and Ehfi Mech, that are considered to be among the top performers. Seachem makes Seachem Matrix, which has some other aspect to it that made me not choose it but I forget what it was (!) and then there are similar products by the mainstream Fluvals and Renas etc.
That all the "noodle" my "Noodle" can think of
~~waterdrop~~
looks lovely .. only problem is i have no knowledge about the carbon filters.
