UV light question

[delmargray]

there are two types of UV tubes: Black light & Black Light-Blue glass

GEs website says the difference btwn BL and BLB is that BLB have dark
glass which traps visible light producing the maximum amount of UV?
this doesnt make much sense to me...having an opaque glass will just
trap visible light not generate more UV, right? or not? thx

[daarrelmills]

UV light is very necessary, Its clear our pond and tank so nicely. It helps to secure our tank from unwanted and harmful bacteria and other worms.