They put out more lumens but think of it this way if 60% of those lumens are in the wrong spectrum then that means its PAR value is around 40% of total light output and do not forget you need to factor in the distance those lights will be away from the plants so you have to apply inverse square law and when you do that you will find HIDs are worse on a watt for watt basis than a decent set of T5 or T8 tubes.
Johnnycannaseed Reviewed by Johnnycannaseed on . Theory about why CFLs don't work as well as HPS etc I've been scratching my head about why people often seem to find that CFL doesn't yield as well as other lighting sources e.g. HPS, as peoples' usual explanations about light not penetrating etc etc don't make much sense to me. Well, I've been trying a CFL grow and I think I have a pretty good answer for everybody now: I bought two types of CFL lights: ones which were advertised as 30W and ones which were advertised as 105W (that's real watts, not equivalent watts). They didn't seem that bright Rating: 5