What difference does having a single end or double end make?

[clownfool]

I have a aquapod 24g with HQI 150w metal halide bulb.
What is HQI mean?
What difference does having a single end or double end make?
Is the DE use less power?
Put off less heat?
Better for my SPS?

[hahnmeister]

you will find what you seek here:
http://members.fortunecity.com/paulerik/

As far as quick response...
1. HQI - Metal halide bulbs with a high CRI (enclosed fixture is usually required) and/or DE/SE European lamps.

2. Bulb selection (some mfgs only make certain bulbs in certain wattages/ sockets) is perhaps the only major thing besides the obvious need for a compatible reflector. But DE bulbs are better built bulbs as well.

3. DE bulbs, meant to be paired up with pulse start or HQI ballasts, use slightly more power than a US spec or probe start bulb listed at the same wattage. They also put out more light for their power rating. They have a higher lumen/watt ratio as well.

4. They both put off about the same amount of heat for the energy they use.

5. SPS can be grown under either. DE bulbs last longer, and have higher outputs than SE bulbs because the DE bulb can be run on a higher current ballast (its a higher pressure bulb) that a SE bulb isnt meant to.

A 150wattHQI is a fine bulb, esp for a 24g aquapod... perhaps the best you can get just short of a 250wattDE bulb/ballast (but that might be too much).