The tetratec ex600 external filter is suitable for aquariums of 60 120 litresr tetratec ex filters are robust easy to use and offer state of the art technology at great value they offer superior filtration over traditional filters helping to make maintaining your aquarium easier and improving the environment for your fishr key benefitsr the tetratec ex filters have been designed with ease of maintenance in mind they not only offer excellent filtration but are simple to dismantle and rea