I'm trying to poke ~150W thru the 18" access hole on the 55Hex I'm planning to buy. I've found 18" VHO bulbs from URI but can find any info on their wattage. Based on scaling a 24" (75W) I'm assuming that these come in about 50W which would require 3 bulbs. This would fit nicely. Anyone know the wattage? tnx jim