Tank : 4ft x 2.5ft x 2.5ft
Sump : 3 ft x 1.5ft x1.5 ft ( 4 compartment) 3 com with coral chips
4in sand bed
25 kg live rock
over flow with bi-ball
de-nitrator
skimmer
Fish : 2 2.5in regal tangs , 1 2in purple tang , 1 2.5 in bi-color angel , 1 2 in flame angel , 1 2in lemeon peel angel , 1 2 in coral beauty , 1 2in clark crown , 1 2in cleaner wrasse , 1 2in royal dottyback , 2 cleaner shrimp , 1 boxing shrimp.
Coral : around 15 pcs of hard coral ( not very sure of their name)
water change is kept at 15percent every 2 weeks. NO3 level is around 25. how can I lower the No3?
BTW is it true that UV light should not be used?