{"id":8155,"date":"2026-11-01T18:59:09","date_gmt":"2026-11-01T18:59:09","guid":{"rendered":"https:\/\/www.rastank.com\/resources\/what-is-ras\/"},"modified":"2026-11-03T13:29:37","modified_gmt":"2026-11-03T13:29:37","slug":"what-is-ras","status":"publish","type":"post","link":"https:\/\/www.rastank.com\/vi\/resources\/what-is-ras\/","title":{"rendered":"What is RAS? Recirculating aquaculture explained"},"content":{"rendered":"<h2>C\u00e1ch ho\u1ea1t \u0111\u1ed9ng c\u1ee7a v\u00f2ng l\u1eb7p<\/h2>\n<p>Water leaving the tanks carries four problems: solids, ammonia, carbon dioxide and a shortage of oxygen. Each treatment stage removes one of them.<\/p>\n<ul>\n<li><strong>Solids removal.<\/strong> A drum filter screens out faeces and uneaten feed. Settlers and protein skimmers take heavier and finer fractions.<\/li>\n<li><strong>L\u1ecdc sinh h\u1ecdc.<\/strong> Bacteria in a biofilter turn toxic ammonia into nitrate.<\/li>\n<li><strong>Kh\u1eed kh\u00ed.<\/strong> A degassing tower strips CO\u2082 from the water.<\/li>\n<li><strong>Cung c\u1ea5p oxy.<\/strong> Oxygen cones or aeration put oxygen back in.<\/li>\n<li><strong>Kh\u1eed tr\u00f9ng.<\/strong> UV or ozone treats the water before it returns to the tanks.<\/li>\n<\/ul>\n<p>A small share of water is replaced each day to control nitrate and make up for losses.<\/p>\n<h2>RAS, ponds and flow-through farms<\/h2>\n<div class=\"table-wrap\">\n<table class=\"spec\">\n<thead>\n<tr>\n<th><\/th>\n<th>RAS<\/th>\n<th>Ao<\/th>\n<th>Nu\u00f4i tr\u1ed3ng n\u01b0\u1edbc ch\u1ea3y qua<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>S\u1eed d\u1ee5ng n\u01b0\u1edbc<\/td>\n<td>Low, water is reused<\/td>\n<td>High, plus evaporation<\/td>\n<td>High, constant supply<\/td>\n<\/tr>\n<tr>\n<td>\u0110i\u1ec1u khi\u1ec3n<\/td>\n<td>Temperature and water quality controlled<\/td>\n<td>Depends on weather<\/td>\n<td>Depends on the source<\/td>\n<\/tr>\n<tr>\n<td>Land<\/td>\n<td>Small footprint<\/td>\n<td>Large area<\/td>\n<td>Needs a reliable water source<\/td>\n<\/tr>\n<tr>\n<td>Running needs<\/td>\n<td>Power, oxygen, trained staff<\/td>\n<td>Lower technology<\/td>\n<td>Lower technology<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>When RAS makes sense<\/h2>\n<ul>\n<li><strong>Water is scarce<\/strong> or expensive to pump and discharge.<\/li>\n<li><strong>Land is limited<\/strong> or close to market.<\/li>\n<li><strong>The climate is wrong<\/strong> for the species, so temperature must be controlled.<\/li>\n<li><strong>Biosecurity matters<\/strong> and you want to control what enters the farm.<\/li>\n<li><strong>You want year-round production<\/strong> at a steady output.<\/li>\n<\/ul>\n<h2>Numbers from a working farm<\/h2>\n<p>A commercial indoor RAS in Sweden held tilapia and catfish water around 30 \u00b0C all year. Energy use was about 3.1 kWh per kg of tilapia and 0.8 kWh per kg of catfish, varying only about \u00b115% between seasons (<a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC7745531\/\">Bergman et al. 2020<\/a>). Power is the running cost that a pond does not have.<\/p>\n<h2>What RAS asks of you<\/h2>\n<p>A RAS depends on power, pumps and oxygen running all day. It needs trained staff, a backup plan for failures, and a design sized on the real feed load. Read <a href=\"\/vi\/resources\/ras-design-basics\/\">Nh\u1eefng ki\u1ebfn th\u1ee9c c\u01a1 b\u1ea3n v\u1ec1 thi\u1ebft k\u1ebf h\u1ec7 th\u1ed1ng RAS<\/a> next, or see <a href=\"\/vi\/projects\/\">our delivered farms<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"<p>A recirculating aquaculture system, or RAS, grows fish in tanks and treats the same water again and again. Instead of drawing new water and letting it flow away, the farm cleans the water and sends it back to the fish.<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_aseo_title":"What is RAS? Recirculating Aquaculture Explained | RASTANK","_aseo_desc":"Recirculating aquaculture grows fish in tanks and treats the same water repeatedly. How the loop works, RAS vs ponds vs flow-through, when RAS makes sense.","_aseo_noindex":false,"_aseo_og_image":8042,"_aseo_schema_type":""},"categories":[1],"tags":[],"class_list":["post-8155","post","type-post","status-publish","format-standard","hentry","category-guides"],"_links":{"self":[{"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/posts\/8155","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/comments?post=8155"}],"version-history":[{"count":4,"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/posts\/8155\/revisions"}],"predecessor-version":[{"id":8525,"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/posts\/8155\/revisions\/8525"}],"wp:attachment":[{"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/media?parent=8155"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/categories?post=8155"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rastank.com\/vi\/wp-json\/wp\/v2\/tags?post=8155"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}