I have used several of the Coralife units in the past and they generally work ok.
The issue is the reflectance factor. The idea w/ any light source is that you need to bounce the light off of the interior surfaces of any cavity in order to fill the room w/ light and achieve max brightness.
A UV sterilizer can be compared to a room in your house. Consider a room in your home that has white walls and a white ceiling, and the floor is a reasonably light and reflective color as well. Now envision any light fixture(s) in it that currently light that room adequately.
Now paint all the walls black and use the same fixture(s).
You'd easily need three times the light in order to have the same working light level in the room.
That's why I shifted over to the stainless Jebao units. After a couple years of having used them I'm a fan and won't buy another Coralife as that black ABS or PVC housing they provide can't have the efficacy of a far more reflective stainless tube and where UV is concerned all you're buying is light... and more light for the same operating cost is nearly always better.