[StirCrazy]

Originally Posted by Funky_Fish14

O yeah Steve,

"of the gas tube type"

MH bulbs also have a gas chamber where the light is emitted from. They dont have a filament.

Chris

your being silly here, I coulden't remember how to spell floressent at the time. and there is a difference becaue a floressent is a gas tube that emits light by exciting the gasses to the point where they emit light, a MH or HID actualy uses a broken filiment and causes a "sustained" spark to jump across the two filiments and create the light output.

Originally Posted by Funky_Fish14

Yeah but steve....the MH will give a much lower PAR rating off to the side of the tank than it would directly below the bulb. Take a reading to a side of your MH and not pointing at it...
Chris

oh ya but ya but, bull malarkie is the best reply for that one you will have the exact drop in intensity off to the side as you would with a floressent tube. (you do know that light radiates at all angles from a MH bulb right?) at anyrate the only drop off by moving to the side is due to an increas in distance (which isn't much) and if you are not holding the measuring insturment corectly (as in keeping it strait up and down when moving to the side) for a proper reading the measuring insturment must alway face the bulb no matter where it is in the tank, so as you move to the side you angle the measuring insterment acordingly. any other variance in intensity from the bottom middle of the tank to the bottom edge is due to pour reflector design or to small of a reflector, and this is the down fall of using a DE type bulb as the smaller reflector makes for a focused light patteren.

Having said that a reflector set up on a floressent T5 bulb can have the same effect by limiting the light out to the sides so with any type of lighting you have to realy look at the reflector design.

even if you have a bad reflector design that does limit the bottom edges of the tank in PAR out put, whoulden't that now be a perfect place to put your low light corals?

Steve