One thing a sump does is help keep the water of your aquarium clean. I covered many of the advantages in the sump post.

There are three primary types of filtration

  • Mechanical – Physically removes unwanted particles
  • Biological – Uses nature’s capabilities to convert toxins into harmless substances
  • Chemical – Usually absorbs unwanted elements

Each of these types serve a different purpose in maintaining an aquarium.

Everyone’s opinion is different

I have read good and bad things about every filtration type. A common chemical filtration is activated carbon. It is very good at removing many impurities from water. It is also what you use to remove medications when you have to medicate a fish. However, I read several accomplished aquarists that will not use it as a filter media. Carbon gets used up over time and can be a source of water contamination. As the carbon becomes used up it can release things into the water instead of absorbing them. These aquarists will not use it for that reason.

My advice is to consider all the opinions and try things for yourself. But the one thing I’ve noticed is that active maintenance seems to avoid every problem people complain about. If you use carbon and don’t like the down sides, you can change it more often.

Most filters have a lifetime

Pretty much all mechanical filters need to be cleaned or replaced on a regular basis. Filter socks are one of the most commonly used in sumps. Various forms of sponge/foam filters are also common. This kind of media needs to be replaced or cleaned on a very regular basis. In fact, many aquarists run their systems without regular mechanical filtration. These guys often rely on a protein skimmer to remove most physical impurities. The theory being that the ocean doesn’t have true mechanical filtration. But it does have a built-in protein skimmer functionality (think about the foam from waves at the shore).

Another interesting filter is seachem purigen. Technically it’s a chemical filtration that targets ammonia, nitrites and nitrates in your aquarium and traps them while allowing good bacteria through. Like most filter media it needs to be cleaned periodically but can be “fully rejuvenated”. I think the biggest flaw with this media is rejuvenating it can be deadly to your tank if it doesn’t go well. The cleaning process involves soaking in a bleach mix. If you don’t get it all out before returning it to your tank, you could kill your fish.

Biological filtration comes in many forms

It can be as simple as growing algae in the tank which naturally extracts impurities from the nitrogen cycle out of the water. A common thing these days is to put “bio media” into your sump. The goal of this media is to give good bacteria a place to live so that it can help filter impurities out of the water. Essentially they become a place to farm good bacteria.

Like most things there are multiple schools of thought in what is the right
shape and material to accomplish this goal. Pictured at the right are ceramic balls and plastic cylinder media.

All those crazy shapesHigh-qualty-font-b-K1-b-font-font-b-filter-b-font-font-b-media-b

First let’s talk about the shape. The idea is simple, the more good bacteria you have, the more filtering power is available. Since this stuff grows on the surface of this media, this means more surface area allows more good bacteria and more filtering. Simple right?

Not exactly. There are a couple of other arguments. The cylinder media technically has more surface area per piece. However all those holes can also trap other things you don’t want in your filter media. In addition, this type tends to do best with an air pump that causes the media to bounce around significantly in their section of the sump. I assume this helps keep the media clear of the things you don’t want it to trap.

product_1427185895Are balls superior?

The ceramic balls by contrast typically have water flow over and through them. Their size matters. Think about a jar of different size marbles. One of big marbles, one of smaller marbles and one of tiny beads. If there were a high flow of water going through each of them, the beads would slow it down because it is too dense. In addition, collections of smaller balls have more surface area collectively than the same volume of larger balls. This means there is a balance in the size that permits good flow, preventing unwanted trapped particles, while providing lots of surface area for bacteria to grow.

In fact, the ceramic balls pictured may arguably be too porous. Smooth exteriors will keep even the smallest unwanted particles from sticking to them. In addition ceramic is effectively glass. You can boil them to return them to their pristine white color. This kind of recharging represents very little risk to your fish especially if you pre-soak them in some tank water extracted from the tank during water changes.

These smooth ceramic balls were specifically selected to compliment the seamless sump system I wrote about earlier. They are also from custom aquariums and you can read more about them here.


Again, I haven’t used this product. I am doing extensive research to find out what I will use in my aquarium. I have thus far liked the logic surrounding Custom Aquarium products. Like everything else, try it. If it doesn’t work as you want, try something else. Either way, I’ve been given a great deal of confidence that their products have a lot of thought put into them.

What do you think about ceramic filtration media?