250w, 400w dimmable or led?

[rives]

Something to keep in mind with dimming is that there is almost always a spectral shift at power settings other than what the lamp was designed for. Also, be cautious about using lower-wattage lamps on a higher-rated ballast set at the reduced wattage - some ballasts handle this fine and put out the correct wattage, others will specifically tell you not to use anything but the high-wattage lamp. Some of them, like the Philips, will put out the full-rated wattage for a period of time while the lamp warms up and then go to the dimmed setting.

 

[testymctester]

Are the cooltubes really effective for keeping it cool? or is it just as good using a normal hood with the vent above?

Cool tubes or air cooled reflectors make a big difference in my small spaces. I run 6-7 degrees above ambient with my tent exhausted directly and my 250w bulb sitting in the reflector without air cooling. I'm 2 degrees above ambient with a 400w bulb in the hood and the exhaust ducted through the air cooled reflector. I'm right at ambient temp with the 250w in the reflector and the ducting running through it.

 

[northern lightz]

would you say I run a higher risk of electric failure and possibly fire? I'm a little nervous about hid lightning and fire to start with.

think I'm gonna go for a 250w mh and a 400w hps that way I will avoid the change of spectrum and save a little money on electricity so I'll be doing a pretty similar setup to yours
testymctester.

If I don't change my mind again that is
think I'm gonna pick up the cheep magnetic ballast too and give cmh a go in the future.

 

[rives]

think I'm gonna pick up the cheep magnetic ballast too and give cmh a go in the future.

You do realize that the CMH and CDM lamps are different and require different ballasts, don't you? The CDM lamps are in the CMH family, but require their own low-frequency electronic ballasts rather than a HPS ballast running at reduced wattage.