i run both on my tank and two DE bulbs are much brighter than 3 SE bulbs of the same color temp and wattage. that is why i run 3 SEs for 8 hours a day and two DEs with them for only 4 hours a day. the SEs seem to produce more shimmer effect than the DEs. BTW, i am running all 250 watt bulbs and the SEs are in luminarc mini knockoff reflectors that i built and the DEs have upgraded reflectors inside the pendants.