Coarse Sponge / Foam Filter VS Fine Sponge / Foam Filter: Which One is Better?

Many aquarists search over the internet regarding the better sponge filter between coarse & fine. In this tutorial, I have explained the Pros & Cons of both Coarse & Fine sponges. The same theory applies for Coarse & Fine foams that are used for Mechanical Filtration media in Internal, Canister & Hang on Back filters.

Fine sponge VS Coarse sponge: Which one is better?
Fine sponge VS Coarse sponge: Which one is better?

Fine sponge / foam offers better mechanical filtration than coarse sponge / foam:

A coarse sponge / foam has larger pores compared to a fine sponge / foam. Sponge filter is used to clean water mechanically by trapping fish waste & other detritus. Coarse sponge cannot trap small impurities due to large pores while fine sponge can collect them. Therefore, for mechanical filtration, fine sponge is much better than coarse sponge. Sponges are not as effective for mechanical filtration because very little impurities can escape them so they are not excellent mechanical filters. Compared to sponges, foams are much more efficient & a fine foam can trap even very tiny impurities.


Both fine & coarse sponge / foam can filter water chemically:

Both coarse & fine sponge / foam can chemically filter water. The goal of chemical filtration is to use filtration media to extract chemicals from the water.


Fine sponge / foam offers slightly better biological filtration than coarse sponge / foam:

Biological filtration breaks fish waste & other debris into less toxic forms such as nitrites & nitrates. The product of the nitrogen cycle is nitrates that are less toxic than nitrites & ammonia. Useful bacteria grow in abundance on surface area after the nitrogen cycle completes. For conversion of ammonia into nitrates, surface area is required for the growth of useful bacteria, water flow will give them access to those nutrients as well as oxygen is needed for breaking down ammonia into less toxic forms. Again, fine sponge / foam is slightly better than coarse sponge / foam when it comes to biological filtration because sponge offers more surface area for the growth of useful bacteria.


Fine sponge / foam needs more maintenance time than coarse sponge / foam:

Fine sponge collects more waste, & it does not leach out waste back into the water when you are taking it out of the aquarium for cleaning. Fine sponge / foam collects more waste so it needs more maintenance time to wash out the gunk. When you are taking coarse sponge out of the aquarium, it releases lots of waste back into the water thus polluting water. When you are cleaning it with de-chlorinated water, it releases the gunk very quickly therefore needs low maintenance time.


Fine sponge / foam clogs quickly than coarse sponge / foam:

If a fine sponge filter is poorly maintained, lots of waste stuck in its pores can clog them permanently thus highly reducing its mechanical filtration efficiency. In addition, its efficiency for cleaning water biologically is highly reduced too as water is not going through the sponge. Therefore, nutrients are not interacting with the useful bacteria growing inside the pores. In addition, low water flow reduces oxygen concentration that can kill the useful bacteria growing inside the pores. Remember useful bacteria do not grow on debris, as they need material for growth, therefore useful bacteria die when debris covers them.

Coarse sponge does not clog that simply as there is more space in between the surface areas of the sponge. 

In the same way, fine foam tends to clog more easily compared to coarse foam. Fine foam clogs faster than fine sponge due to smaller pores.

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