Sera Siporax professional 1000 ml / 290 g

A biological filter medium of sintered glass, 15 mm rings. The 1,000 ml (290 g) pack is sufficient, according to the manufacturer, for 200 litres.

What it suits: freshwater and marine aquariums as well as ponds, and any type of filter – internal, external or trickle.

Why sintered glass rather than fired clay: ordinary filter rings are clay. siporax has a three-dimensional pore structure that maximises the surface area, and the fine pores are a suitable settling surface for bacteria.

The interconnected pore network is what matters: the pores connect throughout, so water rinses the bacteria continuously and they break down pollutants efficiently. The same structure makes the medium self-cleaning, which extends the service interval of the filter considerably.

What is broken down: ammonium, nitrite and nitrate. In nature the surface of the bottom suffices for this, because little waste is produced per volume of water; an aquarium packs the same biotope into a small space.

Pack sizes: 500 ml (145 g, 100 l), 1,000 ml (290 g, 200 l) and 10 l (2.9 kg, 2,000–4,100 l). This is the 1,000 ml pack.