Carbonization is a complex procedure by which the carbon content of organic material is formed by burning anaerobically.
The carbonized base material is then subjected to steam, which increases the pore size and surface area to such extend that one teaspoon of carbon can be compared to the area of a football field.

The increasing of the surface area and pore size is also known as “activation”.
The quality of activated carbon is determined by the carbon base and the above mentioned process, which often includes the use of chemicals and gases, influenced by temperature, burning time etc.
Good quality activated carbon is measured by the iodine number, molasses number.

The iodine number indicates the activity performance level. The higher the iodine number the higher the degree of activation. The iodine number also indicates the micro-porosity (smaller pores equals higher surface).
Iodine numbers vary between 600 – 1200 and mainly adsorb low molecular weight particles, a number in the 1000 range being ideally suited for aquariums.

The molasses number refers to the macro-porosity. Adsorbing more complex (higher molecular weight) particles. A practical number for aquariums would be around 225-250.
Carbon is an organic and all organics contain phosphates. During the manufacturing process, the carbon can be washed using phosphoric, hydrochlorid, or sulfuric acid, to remove inorganic and organic residues.
Acid washing and the removal of organic material will lessen the ash content as well as leachable phosphate. Washing carbon with phosphoric acid does not introduce phosphates.
A well suited aquarium carbon is coal based with an iodine number around 1000, molasses number around 230 and acid washed.

Features of ULTRA-C:
Iodine number: > 950
Molasses number: > 225
Active surface: 950 mq/g
Water content: < 6%
ULTRA-C is available in 1 liter and 5 liters cans.