These LED's just aren't cutting it. Or - are they?

[Ron99]

I doubt that those really cheap generic fixtures are using meanwell drivers or decent LEDs. You just can't get them at that price point. Some other slightly more expensive fixtures may be using Bridgelux LEDs (which are pretty good) and possibly Meanwell drivers. Some may even be using Cree emitters. But there are also different levels within Cree LEDs for example because LED manufacturers bin their LEDs according to output and colour so the higher bins will have higher output and colours closer to their ideal rating. Higher bins are more expensive. So cheaper fixtures are likely using lower bins of LEDs than the more expensive ones.

Can you get good results with less expensive fixtures? Absolutely. But you might not have longevity, maximal output if you need it for a deeper tank, or just general build quality. They have to cut some corners if they are keeping prices down, especially with the really cheap fixtures.

Jakegr: you are correct and I suppose I didn't explain myself fully or clearly. What I meant to say was that blue LEDs emit close to one of the chlorophyll absorbance peaks (as well as the absorbance peak of carotenoids which may or may not be important in corals) so they are providing lots of PAR to the corals even though they may look dim to our eye. So having them run at high output could be bleaching out your corals even though they may seem dim to you.

And it is well known that PAR meters underestimate the PAR at the blue end of the spectrum as most were designed to be used for measuring light for terrestrial applications rather than under water.