Metal Halides & UV Lens, Shields, Filters etc wot the???

[Insect Direct]

Sorry for all the questions I admit I have no idea when it comes to lighting hence why the questions :oops:

Metal Halide

These rate number one for aquarium lighting because of the intensity and spectrum, but a UV lens should be fitted. Bulbs should be replaced at about 12 monthly intervals. However they are expensive to purchase. The unit with bulbs should be suspended well above the water surface because they generate a lot of heat.

Then on my mh glass cover (to cover the light) it says UV FILTER-001

& on the packet for the 150watt mh bulbs ive got it says UV Shield, ultraviolet protection

Now what im getting at is dont plants need and thrive off uv & and what are all these uv shields, filters & lens things doing???

A freind told me a while ago that over the years they've been trying to reduce the uv in which lighting gives off as it is harmfull (causes cancer etc) but if thats true does this mean that the bulbs are no longer as good for the plants in our tanks etc ?

[Ira]

Plants don't need UV. Certainly not the UV that metal halides give off which is UV C which is what UV sterilizers use.. And you need to make a distinction between single ended UV bulbs which have an integrated UV filter and double ended bulbs which do not. And pretty much any double ended MH unit will have the UV filter, which is basically just a piece of glass.