It is not "HQI vs. mogul" but rather double-ended (DE) vs single-ended (SE) metal halide bulbs. SE bulbs are also referred to as "mogul" which is what the socket they fit into is called.
"HQI" is a type of ballast, just like there are "electronic", "pulse" and "probe" ballasts.
HQI ballasts put out more light than other nominally comparable ballasts, but they also use a lot more electricity. For example, a true "250W HQI" ballast will pull upwards of 320W versus 250W for a "250W electronic" ballast. HQI ballasts can run all DE bulbs and most SE bulbs.
How do you tell what kind of ballast you have? Take off the cover and look for the ANSI code. For example, a 250W HQI ballast is an "M80". The exception is electronic ballasts which don't have an ANSI code, but distinguishable by being much smaller and lighter than other types of ballasts.
The main advantage of SE bulbs over DE bulbs is the amount of PAR the gets into the tank since SE bulbs do not require an extra glass UV shield that DE bulbs do. SE bulbs seem to offer a slightly greater spread, but DE bulbs are more compact for tighter spaces. SE bulbs used to have more selection, but DE bulbs (at least at the 150W and 250W formats) have caught up in this regard.
|