| The main reason DE's have such better results in test are becuase the smaller size allows for a better reflector design.
When most reefers taslk about HQI they are referring to the type of ballast you are using. MH ballasts come in four flavors; probe start, pulse start, HQI, electronic. HQI generally puts out the most omph, but also makes the power company the happiest.
If using a DE bulb I would highly suggest getting the electronic ballast.
I don't think you are going to find a retrofit kit for the DE's anytime soon, although you can purchase just the sockets for them. Therefore if you have an appropriate housing for them you can purchase just the socket and retrofit it. However I highly recomend using the pendants, take a look at Sanjay's test, and the pendants really improve the bulbs output over "retrofitted" DE bulbs that are put in quartz halogen housings.
Keep in mind that the DE bulbs have no outer glass housing to block out UV, there they must be used behind some type of glass or you risk seriously burning your corals.
Hope that helps a little bit.
Mike |