Activated Filter Material

What is AFM®?

  • AFM® Stands for Activated Filter Media, a revolutionary filter media made from glass that more than doubles the performance of quartz or glass sand for an existing filtration system.
  • AFM® is bio-resistant and self-sterilising. This makes LSS & RAS systems healthier, more efficient, more stable and more economical.
  • AFM® has successfully been used for over 15 years in seawater intake systems, marine mammal systems and some of the largest and best aquaria in the world.

Your advantages at a glance

  • Crystal clear water – AFM® filtration is much finer and much more stable than quartz sand or normal glass media
  • No Bacteria – Legionella, vibrio, cryptocartyon and many other pathogens grow in the protection of the biofilm. No biofilm means no place for pathogens to hide in the filter.
  • pH stability - No bacterial nitrification in the filter that would otherwise depress the pH. Biofiltration can be deported to a more appropriate, well aerated vessel.
  • Reduced bioload - No bacteria means less total load on the system and lower chlorine consumption in chlorinated systems
  • No smell of chlorine – No heterotrophic bacteria means no trichloramine and thus no disturbing smell and harmful disinfection byproducts.
  • Ecological and economical – No Biofilm means AFM® saves energy and chemical consumption by filtering more efficiently and saves 50% of backwash water compared to sand.

Filtration performance:

AFM® 1 filters without flocculation down to 1μ at a velocity of 20m/hr. It retains at least 30 % more organic substances than fresh sand or glass media. In chlorinated systems with optimised coagulation and flocculation with APF and ZPM, a nominal filtration of 0.1 micron will be achieved.
AFM® is bioresistant, it offers no home for bacteria, viruses and other pathogens.

The independent testing laboratory IFTS (Institute of Filtration and Techniques of Separation) tested different glass filter media and sand and approved AFM® to be the best available filter material on the market. In addition, AFM® is NSF/ANSI 50, NSF/ANSI/CAN 61 certified by WQA and therefore approved for swimming pools and drinking water applications.

Fish Systems

Stable sub 5μ filtration

Sand is a good mechanical filter but also provides a perfect support for bacterial growth as every grain of sand is colonised by bacteria within a few days. Mechanical filtration is compromised by bacterial nitrification that consumes oxygen from the water, depresses the pH and causes anaerobic coagulation of the sand. Clogging causes channeling of the bed and sporadic release of filtered material and undesireable pathology into the process water.

AFM® is not compromised by bacterial growth and provides stable sub 5μ filtration for reliable mechanical filtration and evacuation, even of Cryptocaryon oocysts, in backwash.
No bacteria means no biofilm in the AFM® filter and no channel formation to disrupt the filter function. The performance of AFM® remains consistently high for 10 - 15 years.

Chlorinated Mammal Systems

Less trichloramines

Bacteria settling on sand media immediately excrete a mucus biofilm to protect themselves against the disinfectant. Entire communities of bacteria live in the biofilm including legionella, vibrio and other undesireable pathogens.
Bacteria in the biofilm convert urea to ammonia which then reacts with chlorine to form inorganic chloramine (mono, di- and trichloramine) and trihalomethanes.
Trichloramines are responsible for the unpleasant chlorine smell and also present a severe animal health hazard. AFM® does not support bacteria and there will therefore be no biofilm and hence no pathogens housed within it. If there are no bacteria urea will remain in the water and reacts with chlorine to form harmless, odourless chlorurea.

No bacteria → no biofilm → less trichloramines → no chlorine smell → no pinniped eye irritation → no cetacean pulmonary irritation → no walrus skin irritation.

No bacteria → lower chlorine demand → less chlorine consumption → less Disinfection By-Products (DBP‘s):

Chlorine reacts with organic and inorganic substances and produces undesirable, harmful reaction by-products such as trichloramine and Trihalomethanes (THM‘s).
With AFM® and effective coagulation and flocculation we remove far more substances than with sand or glass media. The better the filtration the lower the chlorine consumption and less disinfection by-products are produced.

Dryden DAISY® filter circulation for private pools:

Operating criteria

  • Filtration velocity: 1 - 30 m/h
  • Backwash velocity: 40 - 50 m/h
  • Backwash duration: 3 - 10 minutes
  • Max. operating differential pressure: 0.5 bar
  • Water pH limits: 3 - 9
  • Water temperature limits: 1 - 100 C
  • For AFM layering details, refer to IFU Instructions for Use Document

AFM® Grade 1 specification

  • Bulk bed density: 1‘250 kg/m3
  • Effective size: 0.45 mm
  • Spherizity: 0.75 - 0.80
  • Uniformity coefficient: 1.6 - 1.8
  • Aspect ratio: 2 - 2.4
  • Specific gravity: 2,4 kg/l
  • Organic contamination: < 50g/ton
  • Color purity: > 98%
  • AFM® is supplied in 21 kg (47 lbs), 25 kg (55 lbs) or 1000kg (2200 lbs) bags
  • AFM is available in 4 grades

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Contact us

Dryden Aqua Ltd
Production, Research & Development
Butlerfield Ind. Est Bonnyrigg
EH19 3JQ
United Kingdom
Phone: +44 1875 822222