Water does not equal water! There are numerous different kinds of waters. Especially tap water differs from region to region very drastically because of different water sources like reservoirs or ground water. In some regions tap water needs to be chlorinated before it gushes from the tap, in other regions the tap water has a better quality than the table water. As a rule, most waters are purified for us Humans in a manner that the most germs are being neutralised the good as well as the bad ones. Fluval?s - Biological Water Additive return exactly this selected proportion of helper bacteria to the aquarium water. These invisible helpers are essential for the recycling of fish waste, food residues and the prevention of algae. The right water conditioners ensure balance right from the start-up phase and also ensure that tap water can be used for the aquarium without hesitation. The Fluval water conditioner, for example, binds harmful heavy metals from the water and can even render chlorine and chloramine harmless. The biological water additive has the potential to drastically shorten the start-up phase of the aquarium. In this category you can buy a lot of helpers for increased water quality.