What is AFM?


Prevent Bacteria rather than killing it!


Activation process: The AFM® activation process creates a mesoporous structure with a huge catalytic surface area. Typically crushed glass or sand has a surface area of 3‘000 m2 per m3 but activated AFM® has a surface area of over 1‘000‘000 m2 per m3 which is over 300 times greater surface area for adsorption and catalytic reactions.


Hydroxyl groups on the surface give AFM® a strong negative charge known as the zeta potential that attracts heavy metals and organic molecules. In the presence of oxygen or oxidising agents the catalytic surface generates free radicals that oxidise pollutants and disinfects the surface of AFM®.


  • AFM® stands for Activated Filter Material, a revolutionary filter media made from green glass developed and manufactured by Dryden Aqua.
  • AFM® exceeds the performance of quartz and glass sand by filtering about 30 % more organics.
  • AFM® is bio-resistant and self-sterilising which means no biofilm is formed in the filter bed. This important feature makes the pool system healthier, ecological and more economical.
  • AFM® has successfully been used in over 100‘000 public and private swimming pools worldwide.
  • AFM® is manufactured under ISO 9001-2008 standards and is a filter material certified under European standards for drinking water.
  • AFM® is a registered trademark and is exclusively made by Dryden Aqua.


AFM® exceeds the performance of quartz and glass sand by far



Crystal clear water: AFM® filters much finer than quartz or glass sand. At 20 m/hr filtration speed a nominal filtration of 5 microns is achieved without flocculation – AFM® filters at least 30 % more organic substances than fresh quartz or glass sand. With optimised coagulation and flocculation with APF and ZPM, a nominal filtration of less than 0.1 microns can be achieved.

Lower chlorine consumption means less secondary chlorine reaction products: chlorine is an excellent disinfectant. But in reaction with organic and inorganic substances it also produces undesirable, harmful reaction by-products such as trichloramine and THM‘s. The more chlorine is consumed the more secondary reaction by-products are produced. With AFM® we can remove far more substances than with sand or glass sand. This applies particularly in connection with coagulation and flocculation. Everything that can be filtered out and removed in backwash process doesn’t have to be oxidised. The better the filtration the lower the chlorine consumption and less disinfection by-products are produced.

Bioresistant – no home for bacteria, viruses and other pathogens: sand is a good mechanical filter but it’s also an ideal breeding ground for bacteria. Within just a few days every grain of sand is colonised by bacteria. They immediately form mucus to protect themselves against the disinfectant. In this so-called «biofilm» live entire communities of bacteria and other pathogens – including Legionella. If you have no organic film in your filter there are also no Legionella.

No trichloramine and no chlorine smell: the bacteria in the biofilm convert urea into ammonia which then reacts with chlorine to inorganic chloramine (mono, di- and trichloramine). Trichloramine causes the unpleasant chlorine smell and is also a severe health hazard. If however, no heterotrophic bacteria are present, urea remains in the water. It reacts with chlorine to the harmless chlorine urea. No biofilm – no trichloramine - no chlorine smells.

Filter function remains good with AFM® for many years: No biofilm in the AFM® filter also means no channelformation to disrupt the filter function. Due to filter contamination the performance of a sand filter worsens dramatically after 6 - 12 months despite frequent backwashing. The performance of AFM® remains consistently high for many years.


      Your advantages at a glance

      • Crystal clear water - AFM® filters at least 30 % better than silica or glass sand.
      • Lower consumption of chlorine - Everything filtered out doesn´t need to be oxidized by chlorine. The better the filtration, the lower the chlorine demand.
      • No trichloramine – no chlorine smell: AFM® prevents growth of biofilm therefore eliminating trichloramine.
      • No biofilm – no Legionella: Biofilm is a slippery film of bacteria, most of which are friendly, but they provide a home for pathogens such as Legionella, Staphylococcus and (MRSA) Pseudomonas.
      • Chlorine-free systems - AFM® greatly reduces the oxidation demand of the water which makes it perfect for chlorine free systems.