{"id":8145,"date":"2026-11-01T18:59:03","date_gmt":"2026-11-01T18:59:03","guid":{"rendered":"https:\/\/www.rastank.com\/resources\/oxygenation-in-ras\/"},"modified":"2026-11-03T13:29:32","modified_gmt":"2026-11-03T13:29:32","slug":"oxygenation-in-ras","status":"publish","type":"post","link":"https:\/\/www.rastank.com\/id\/resources\/oxygenation-in-ras\/","title":{"rendered":"Oxygenation in RAS: degassing, PSA oxygen and cones"},"content":{"rendered":"<h2>Where oxygen goes<\/h2>\n<p>Fish use oxygen to breathe and grow. The biofilter bacteria use it too, and so does any organic matter left in the water. Demand rises with feed and with temperature, while warm water holds less oxygen.<\/p>\n<h2>Aeration or pure oxygen<\/h2>\n<p>Blowers and diffusers add air. They are enough at lower stocking densities and are always needed for MBBR biofilters and degassing. At high density, air alone cannot keep up and pure oxygen is added.<\/p>\n<h2>Remove CO\u2082 first<\/h2>\n<p>CO\u2082 harms fish even when oxygen is fine. In a pikeperch RAS trial, feed conversion worsened from 1.09 at 5 mg\/L CO\u2082 to 1.82 at 30 mg\/L (<a href=\"https:\/\/www.frontiersin.org\/article\/1812125\">Frontiers, pikeperch trial<\/a>). Cold-water species are often given a tolerance of about 10\u201320 mg\/L and warm-water species about 20\u201340 mg\/L (<a href=\"https:\/\/cdn.prod.website-files.com\/68f8fef97a0ec0c0367da245\/695c1866053a823aec0d0de7_1-FloNergia%20-%20CO2%20Stripping%20Report.pdf\">FloNergia<\/a>). A <a href=\"\/id\/equipment\/degassing-tower\/\">menara degassing<\/a> strips CO\u2082 as water falls through packing against a flow of air.<\/p>\n<h2>Making and dissolving oxygen<\/h2>\n<ul>\n<li><strong>PSA generators<\/strong> make oxygen on site from air, so the farm does not rely on deliveries.<\/li>\n<li><strong>Kerucut oksigen<\/strong> dissolve it under pressure into the return flow, so little is lost.<\/li>\n<li><strong>Standby supply<\/strong> covers a generator stop or power failure.<\/li>\n<\/ul>\n<p>See <a href=\"\/id\/equipment\/oxygen-generator\/\">Generator oksigen PSA<\/a> dan <a href=\"\/id\/equipment\/oxygen-cone\/\">kerucut oksigen<\/a>.<\/p>\n<h2>Size on the peak<\/h2>\n<p>A common rule of thumb is about 350 g of oxygen per kg of feed for the fish (<a href=\"https:\/\/www.novair-usa.com\/how-to-estimate-oxygen-requirements-in-aquaculture\/\">Novair<\/a>). Average oxygen demand is still the wrong number. Size on the demand after the largest feeding of the day, at the warmest water temperature you expect, and add a standby. The first layout we send shows this oxygen balance.<\/p>\n<h2>Watch it<\/h2>\n<p>Dissolved oxygen falls fast when a pump, blower or oxygen supply stops. A sensor and alarm on dissolved oxygen is one of the most useful things a farm can fit. One farm manager\u2019s fish survived a 20-minute outage only because backup oxygen opened by itself (<a href=\"https:\/\/www.globalseafood.org\/advocate\/backup-oxygen-power-systems-essential-insurance\/\">Global Seafood Alliance<\/a>). See <a href=\"\/id\/equipment\/monitoring-control\/\">pumps, drains and controls<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"<p>In a dense RAS, oxygen usually limits the farm before space does. Fish use most oxygen just after feeding, and they breathe out CO\u2082 that builds up in a closed loop. Both have to be managed.<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_aseo_title":"Oxygenation in RAS: Degassing, PSA Oxygen, Cones | RASTANK","_aseo_desc":"Oxygen usually limits dense RAS before space does. Remove CO\u2082 first. Make and dissolve oxygen. Size on peak demand after feeding, not average.","_aseo_noindex":false,"_aseo_og_image":8056,"_aseo_schema_type":""},"categories":[1],"tags":[],"class_list":["post-8145","post","type-post","status-publish","format-standard","hentry","category-guides"],"_links":{"self":[{"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/posts\/8145","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/comments?post=8145"}],"version-history":[{"count":4,"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/posts\/8145\/revisions"}],"predecessor-version":[{"id":8520,"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/posts\/8145\/revisions\/8520"}],"wp:attachment":[{"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/media?parent=8145"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/categories?post=8145"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rastank.com\/id\/wp-json\/wp\/v2\/tags?post=8145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}