Amanzi akumgangatho ophezulu ancedisa ukukhula kwentlanzi (amanzi akumgangatho olungileyo = ukukhula ngoku khawuleza), ukubakhona kwesifo kunye nencasa, nombala wentlanzi. Umgangatho wamanzi uchazwa zizinto ezine ezibalulekileyo:
Ubushushu bamanzi
Amazinga we oxygen emanzini
Amazinga we Ammonia emanzini
I-pH Emanzini (ubungakanani be acidity okanye alkalinity)
Iingxaki ezininzi zomgangatho wamanzi acocekileyo kwimfuyo yentlanzi zenziwa kukuphela kwe oxygen, amazinga aphezulu we ammonia, okanye amazinga aphezulu we pH. Ezingxaki zisondele kwinqanaba lobulembu obuhlaza obuncinci emanzini.
Ukukhula kobubulembu buxhomekeka kubuninzi be nutrients-nitrogen (N) kunye ne phosphorus (P) – emanzini. Ezi nutrients zingena edamini nge:
Ngamanzi (Angenayo edamini).
Ukungena kobumdaka xa kuthe kwanetha kakhulu (imvula egqithisileyo).
Ukutya kwentlanzi ngexesha lemveliso.
Ubushushu Bamanzi Ekulimeni Intlanzi
I-Trout ikhula kakuhle phakathi ko 14 kunye no 18℃ (16℃ ubushushu obulungileyo bamanzi) kodwa iintlobo ezishushu ezifana ne sharptooth catfish zikhula kakuhle kumanzi ashushu (20 – 30℃) itilapia amazinga amanzi ashushu we 24 -34℃.I-Trout ayidibani namanzi ashushu. Ubushushu obungapha kwama 20℃ buzakwenza itrout iyeke ukukhula kwaye oku kwenze ezinye iingxaki kwimveliso, esifana nokongezeleka kwezifo nengxaki ze oxygen uyacacisa uHenk Stander oyinqnunu yomphathi kwicandelo le Aquaculture Department of Animal Sciences, Stellenbosch University.
Zingxaki (ukonyuka kosuleleko lwezifo kunye nokwehliswa kwe oxygen) zenziwa bubulembu obuhlaza obuncinci kumanzi ashushu (microscopic algae). Xa ubushushu bufikelela kuma 21℃ nangaphezulu, kufuneka kuqwalaselwe ukuthintela ukufa kwentlanzi kunye nongcoliseko lobulembu. Ungcoliseko lobulembu obuhlaza benziwa kukongezeleka kwabo ngokwenani oko kusenziwa ngamazinga obushushu aphezulu nokungabikho kwe nutrients. Ubulembu bukhupha ikhemikhali enukayo, i-geosmin. Lomgubo xa utyiwe yintlanzi utshintsha incasa yenyama yentlanzi.
Amazinga we Oxygen Kulimo Lwentlanzi
Iingxaki ze oxygen kakhulu zenziwa bubulembu obuncinci obungabonakaliyo. Obu bulembu buncinci benza buvelise i-oxygen. Kumazinga aqhelekileyo, akuzubakho ngxaki.
Xa amazinga wobulembu esanda, amazinga we oxygen ebusuku angabasezantsi kuno 5 mg/L kwaye kuza kubakho iingxaki ze oxygen emanzini ngentseni elandelayo.
Okwesibini, xa kukho ubuninzi bobulembu obuncinci obufayo (ngenxa ye simo sezulu esisibekeleyo okanye ukukufafaza ialgacides) i-aerobic bacteria izakukhula kakhulu ukuncedisana nokungcwaba ubulemu obufileyo. Le aerobic bacteria itya i-oxygen ethi yehlise kwa amazinga we oxygen kumadama ngoku khawuleza yenze intlanzi zibe phantsi koxinzelelo.
Amazinga we Ammonia Kumanzi Acockileyo
I-Ammonia yenzeka kwindawo enobumdaka (ayikho i-ammonia) nenga ngcolisekanga (ionised ammonia) kodwa ukungcola buba ngaphantsi ko 10% be ammonia yonke exutyiweyo. Kumanzi ashushu (+20℃ ) ne pH ephezulu (8.5), amazinga we ammonia emdaka azokongezeleka.
Amazinga we ammonia awazukwenza iingxaki kumadama ngaphandle kokuba asezantsi (5 m okanye ngaphantsi) nengeniso encinci ngonyaka okanye engaphantsi kwenye. (‘Annual turnover’ bubuninzi bamanzi obudingekayo ukuze kugcwale idama yimvula okanye amanzi agalelweyo).
IpH Yamanzi we Dama
Eyona nto ibalulekileyo ezakonyusa amazinga we pH kukukhula kobulembu obuncinci. Ubuninzi bobulembu bungongeza ipH ingakumbi kumadama akwifama ezincinci kumazinga angaphezulu kwi pH engu 9 (ingakumbi emveni kwemini). Oku kwenziwa kukususwa kwe carbon dioxide ngexesha lakumatshona kwelanga. I-pH ephezulu izakufaka iintlanzi phantsi koxinzelelo.
Ukunciphisa okanye ukwenza ngcono lamanqanaba, kufuneka kutshintshwe amanzi, yongeza amanzi acocekileyo xa kukwazeka, kungenjalo faka ibarley straw.
Translated by Zikhona Plaatjie