400w HQI Ballast

ocboat · Feb 28, 2019

I dug an older 400w hqi ballast out of storage and am thinking of running it over my 36"x36" cube with a large Lumenarc SE reflector. From reading older threads, it looks like the 400w Radium bulb is manufactured differently and should not be over driven. Does that only leave the Giesemann bulbs for 400w hqi ballasts? Has anyone compared the 17500k to the 21000k on this ballast and how would you describe the color? Thanks.

PaulErik · Feb 28, 2019

Radium did change the 400 watt 20,000K lamp a few years ago. The new one is a hit or miss when overdriving.

The 400 watt Giesemann and Ushio none CWA models will work best with a HQI ballast.

The 17500K is white with a blue/pink tint. Some people find it too white or pink after burn in.

The 21000K is blue/white with a slight violet tint. The the Ushio 20,000K+ looks the same. They both look similar to a none overdriven Radium and is a good choice when using a 400 watt HQI ballast.

Hot2na · Mar 1, 2019

If I had that ballast -I'd get myself an iwasaki 6500k bulb and surround it with 2 orphek uv/violet led bars .....can you say growth ?

jda · Mar 1, 2019

The Hamilton 400w bulbs will last on that ballast too. ...just about anything but the new Radium. The only guy that I know that uses this combo switched to the 21k Giesemann and changes them at 6 months.

Off topic, but I got to see the mess that an exploded Radium made... do not take a chance on this.

PaulErik · Mar 1, 2019

I personally would stick with lamps that are designed to handle the lamp/arc current from that ballast.

Using lower current rated lamps like the Hamilton and Iwasaki lamps will cause the lamp and also the ballast to operate out of spec. I’ve seen premature capacitor failure and shorted primary/secondary coils from not using the correct lamps. With magnetic ballasts it is important to properly match the lamp and ballast types.