In 1992, the French Avignon raceways, 
densely stocked with trout,
experienced serious problems, including 1.5 feet (0.5 meters) of sludge
build-up, high levels of suspended solids, ammonia spiking, and high BOD.
This generally poor water quality produced a 15% mortality rate in the trout
crop.
The unhappy trout farmers first considered draining and dredging the raceways. The high cost of dredging and disposing of the sludge, coupled with the loss of income from ceasing trout production for the duration of treatment, weighed against this option. The farmers decided, instead, to increase the flushing rate to 40%, accepting escalated water bills. This option was ineffective and fish continued to die off.
Looking for solutions at an aquaculture trade show, the trout farmers heard about Alken-Murray Corporation's successful results treating the Moulin Vert Canal and immediately placed an order for Alken Clear-Flo® 1200.
While willing to try this new product, the farmers were cautious
enough to insist on maintaining their high flow rate. The first dose of
Alken Clear-Flo® 1200 was adjusted to 8 gallons, to compensate
for the short retention time.
After the first week, 10 cm of sludge was reported degraded, ammonia levels were greatly reduced and BOD began to fall. Gaining confidence, the trout farmers decreased the flow rate and reduced the dosage of CF 1200 to 2 gallons a week. Sludge continued to degrade at a rate of 10 cm/week, until it was totally decomposed. The mortality rate reduced to 5% (a 66% improvement). As a bonus, the lagoon, into which the raceways drained, became free of algae and suspended solids.
After 2000, Alken-Murray would advise a combination of Alken Clear-Flo®1005 to remediate sludge alternated with Alken Clear-Flo® 1006 to clean water and improve fish health. Alken Clear-Flo® 1100-50x is used when ammonia levels exceed those required by heterotrophic microbes to balance organics present, for complete digestion. of both. These new highly concentrated formulas provide greater control and economy, reducing freight costs significantly, while the powdered products maintain room temperature shelf-life for two years and the nitrifiers remain stable, under refrigeration, for one year, comparing favorably with the 3 to 6 month shelf-life of Alken Clear-Flo®1200
