What is a Filter Raceway System?   

A Filter Raceway system is essentially a "clarifier".  The purpose of this filter raceway is to remove settled and suspended solids (floc) on a continuous basis from the grow-out tank.  This closed-loop water recirculation/filtration system is consists of one round tank connected to one filter raceway (as shown in the photo).  The water from the round tank gravity flows to one end of the filter raceway where the filter media, made of discarded monofilament fishing net, to trap or filter suspended organic matter (floc, feces, algae, etc) through a series of three chambers before pumping back to the round tank.

An 800 m2 round tank (32 meters in diameter) or 1,000 m3 water volume requires one filter raceway of 5% the volume of the round tank or 50 mt volume.  A two HP submersible pump provides a continuous recirculation of water from the filter raceway to the grow-out tank (approximately 22 hours per day).  The recirculation is stopped for two hours to clean the filter nets in the raceway sections and discharge the accumulated sediments.

This continuous "polishing" or reducing the amount of sediments and suspended floc during the culture period significantly reduces overall water exchange.  This results in cost savings of water storage, treatment (chemicals) and effluent discharge into the environment.  

In addition, returning or recycling "mature" culture water from the filter raceway back to the grow-out tank maintains a more balanced microbiome which lessens the need for commercial bio-remediation probiotics and synbiotics.  Farmers using this filter raceway or clarifier system claim to gain an additional two kilos of shrimp biomass carrying capacity by recycling mature water (from 6 kilos/m2 to 8 kg/m2).