Article: by Brynn Simpson Photos supplied T wo Dam Sustainable is a small trout farm operated by Marco and Vivian Harms on Langhoogte Farm, up a dead end valley outside of Montagu. Two things make Two Dam Sustainable remarkable (besides the quality of their smoked trout products, obviously!). Firstly part of their production comes from a Recirculating Aquaculture System (RAS) and secondly they operate off the power grid. The recirculating aquaculture system, built by Deep Blue Aqua, is a moderately complex aquaculture system whereby water is reused many times over prior to being sent to waste. Solids are removed and bio-filtration is used to convert toxic ammonia produced by the fish to non-toxic nitrates that are removed through water replacement. Alt- hough there is a continuous flow of new water into the system, it is designed to operate with a low replacement rate (daily replacement of 15% of the total tank volume). In an area like Montagu where water is scarce in summer, that’s important. Water is plentiful and cold in winter but summer presents a more stressful situation for Marco and all his trout as water flow volumes in the nearby river fall dramatically and temperatures start to rise, exceeding 25oC. Marco’s challenge has been controlling the heat in the system. Cooling was an imperative, but without the option of using energy hungry equipment. A combination of evaporative cooling systems and new water fed from a deep borehole has allowed Marco to continue production right through summer. Being “powerless” has presented a host of challenges to the Two Dam Sustainable team. The farm has no Eskom or Municipal power connection, leaving alternative energy as the only possible sustainable source of power. Marco has made use of solar panels and a water turbine to provide power for the trout farm and has installed an LP gas generator as an emergency back-up. Marco’s smoked trout is gaining quite a reputation in the local area and beyond. Two Dam Sustainable supplies trout to a number of local restaurants and is often seen at local markets on the weekend. You can get hold of Two Dam Sustainable at email@example.com and Deep Blue Aqua at www.deepblueaqua.net.