▁so . ▁ ▁The ▁spent ▁h ops ▁are ▁removed ▁from ▁the ▁bitter ▁liqu or ▁by ▁dec ant ing ▁or ▁' cast ing ' ▁it ▁into ▁the ▁hop ▁back , ▁a ▁vessel ▁on ▁the ▁ground ▁floor ▁beneath ▁the ▁co ppers . ▁The ▁spent ▁h ops ▁sett le ▁out ▁and ▁the ▁liqu or ▁is ▁stra ined ▁through ▁them . ▁ ▁A ▁non - gravity ▁process ▁now ▁takes ▁place , ▁where ▁the ▁liqu or ▁is ▁p ump ed ▁back ▁up ▁the ▁tower ▁to ▁cool ers ▁in ▁the ▁fourth ▁floor ▁att ic . ▁A ▁green ▁or ▁un fer ment ed ▁w ort ▁still ▁at ▁bre wing ▁temper atures ▁would ▁kill ▁the ▁ye asts ▁used ▁in ▁fer ment ation , ▁so ▁must ▁first ▁be ▁co o led . ▁ ▁Co o led ▁liqu or ▁flows ▁down ▁to ▁the ▁first ▁floor ▁and ▁the ▁fer ment ing ▁t uns . ▁Ye ast ▁is ▁added ▁and ▁fer ment ation ▁begins . ▁Fer ment ation ▁takes ▁around ▁a ▁week ▁and ▁a ▁large ▁bre wer y ▁may ▁have ▁enough ▁fer ment ation ▁volume ▁to ▁contain ▁several ▁bre ws ▁simultaneously . ▁The ▁large ▁area ▁needed ▁often ▁extends ▁into ▁a ▁lower ▁building ▁alongside ▁the ▁bre wing ▁tower . ▁Tow ards ▁the ▁end ▁of ▁this ▁time , ▁the ▁ye ast ▁is ▁removed . ▁ ▁Be er ▁from ▁the ▁fer ment ation ▁vessels ▁is ▁run ▁to ▁storage ▁on ▁the ▁ground ▁floor ▁below . ▁Here ▁it ▁may ▁be ▁cleared , ▁filtered ▁and ▁stored ▁before ▁being ▁ra ck ed ▁into ▁c ask s ▁kept ▁on ▁a ▁still age .