which one should i choose to use on my 6 plant aeroponic system im leaning towards a led because they save money on electiricy and then run a lot cooler than hps lights if i use the hps im going to have to setup a really expensive intake and exhaust system to keep it cool in my closet what should i do?
You deffiantly should get the 400w HPS you will be more satisfied with the end results and as far as power consumption you will be rewarded with much more buds for the extra cost of runing the better light. If you buy a digital ballast they are slightly cheaper to run then your standard magnetic coil type. It seems your concerned about ventiltion prices but they may be cheaper then you think. Check out www.plantlighting.com they will have very affordable inline fans.
yeah LED's are great in theory, but technology has not yet caught up with them, and they are not as efficient yet