View Full Version : 400w radiums vs. 400w xm's 20k

07/27/2006, 11:42 AM
give honest opinion on this two bulbs. i know radiums have to be c/n every 6 month or so,what about xm's? I've heard radiums gives pretty good color. I have hqi ballast right now.
Wich bulbs i should get?


07/27/2006, 12:09 PM
XM will last longer, but the radium has a nice color and par is gewd.
Xm 400 has good par too, Perosnally I would do the XM

07/27/2006, 12:32 PM
Ran both, love both! But... I like the XM better.

07/27/2006, 12:37 PM
Thankx guys for respond.
but ,why u would prefer xm's?

07/27/2006, 01:16 PM
XM lasts longer, so XM gets my vote

07/27/2006, 01:32 PM
Just because of that,ok... but, how about colorwise, par?
radiums has more par value over xm's?

David Grigor
07/27/2006, 01:59 PM
I've used both Radiums for about 4 years and XM for about 1.5 years.

I didn't find Xms to last any longer. About 6-8 months regardless which bulb. Radium on my sungro ( HQI) ballast ran slightly whiter than the XM.

I no longer use MH but I think it's a total toss up with slight edge to XM because of price and availabilty.

07/27/2006, 02:47 PM
The Radium is a bit more purple and the XM is a bit more blue. With actinics you get a purple glow already, so to me the XM looks better. I don't run them on HQI ballasts, so the XM has more par as well for my setup.

You can't go wrong with either bulb if you like the look.

07/27/2006, 09:11 PM
thanx for suggestions and opinions.. i think i will go with radiums


Eric Boerner
07/28/2006, 01:45 AM
9 months on my XM's on 3 replacements. Like the baby blue look with good actinics with the bulbs, vs the hardcore purple and heavy actinics from the radiums. Plus the XM's are $20-$30 cheaper per bulb.

john f
07/28/2006, 04:25 AM
Radiums run on the HQI ballast look identical to XM 20k run on standard ballasts, at least to my eyes.
I also think the XM may last a little longer, but I need to test that with my light meter.
The problem in testing is that light meters don't read blue very well, so I'm not sure the values given mean too much, and our eyes don't see blue too well either.

I wish someone made a light meter you could adjust, say to look for 400-500nm range only.


07/28/2006, 08:40 AM
how do XM's looks on HQi ballast? MOre bluer or whiter?
i have a new t5 actinics with is very nice as far as color and compare to vho.
So, u guys still recomend me to get a Xm's?


David Grigor
07/28/2006, 09:46 AM
Me personally, I don't see the purple vs. blue comparison but eye perception is not the same for everyone.

On an HQI ballast, If you have run Radiums before they start out bluer and whiten up some over about 2 weeks time some. While the XM on HQI ( at least my experience ) looks more like a brand new not broken in yet Radium which is a little more blue. Not a drastic difference to the two IMO but XM is a little bluer after burn in. I didn't see any bulb life difference on the HQI both around 6 month and 8 month max before you start seeing some SPS corals start to loose a little color.

As far as corals go, I don't really see any pro or con to the Radium, they both do a very good job. I would lean towards whichever bulb you can get the better deal and availablity on.

07/28/2006, 10:13 AM
<a href=showthread.php?s=&postid=7826078#post7826078 target=_blank>Originally posted</a> by MSHUR
Just because of that,ok... but, how about colorwise, par?
radiums has more par value over xm's?
Good color, decent par, corals looked great.
I really liked the XM

07/28/2006, 10:16 AM
Thankx guys,
I've heard xm's runs better of m59 ballast ,is that so?
i do have pfo hqi right now and i dont think i would spend more $$ to get m59.. i always tought pfo is the best

David Grigor
07/28/2006, 11:51 AM
Even on HQI it's pretty much a toss up which one you choose. The differences are pretty subtle and doubtful you will seen any difference with how your corals react between the two bulbs which is the most important thing.

07/28/2006, 12:08 PM
Thank you David
I will try Xm's first....BUt, Ive heard radiums have more par from hqi ballast ,vs xm