uv questios

[mycat99]

ok i have bine told bye 1 fish store that these are not worth the money and bye onter that i have to have on .my tank is only live rock with few fish .also what size uv do you need on a 90 gallon .was told the coralite 9watt would be to small and would need a 18 watt one .also roughly how much water flow do you need in a tank .with my canister /koralia 1and 4 pump and my skimmer my flow rate is around 2400 gph .again was told it sould be 9X the size of tank.thanks