our 130 ltr ran for a year with no skimmer and it was fine,changed 10 to 20 ltr a week and fish were healthy,simple mush and zoas etc were ok too,altho after getting white spot introduced with a new fish i cant recommend a uv light enough,think it was about $60 and that and adding abag of carbon made the water like glass and took any yellow out of it,i have just added a reefoctopus hob skimmer because want to try fussier corals now and it was $250 new,