Just got these bulbs from EricF. I put 1 side by side w/ a radium on a pfo magnetic pulse ballast. They look very similar, and for a considerable price difference.
Radium 250w 20k SE
Pros:
Crisp white color w/ blue tint
Makes the color of corals pop
No actinic supplementation needed
Cons:
Price
Must be run on a pulse start, HQI, or electronic ballast
Helios 250w 20k SE
Pros:
Crisp white color w/ blue tint
Pops red orange and yellow better than the Radium
No actinic supplementation needed
Cheaper than the Radium
Cons:
Don't know yet
RESULTS:
The Helios 20k SE bulb is a great alternative to the Radium for 2 reasons: price and similar (if not better) performance. According to fragfarmer.com amd Sanjay's test, the Helios has more par than a Radium.
http://www.fragfarmer.com/250watt-20...ase-p-508.html