20K DE Bulb Reccomendation for M80 (HQI) Ballast

[mikerobart]

I have looked around at some other forums, and will have a closer look at Sanjay's spectral plots later, but I want to ask you guys anyways.

Current running 2x250W MH + 2x24W PC in an Aquamedic fixture. From what I have dug up, the internal ballasts are the magnetic kind, M80, or a "true" HQI ballast.

These tend to overdrive bulbs well past 250W, although I need to confirm at some point with a watt meter. Anyways, it seems bulbs generally burn much whiter with these ballasts than on an electronic ballast.

My Phoenix 14K started as a very crisp pure white with a hint of blue and after burn in now burns pure white... not really any blue.  My weak actinics aren't cutting it.

I want to try some 20K bulbs ( I like blue!) ... but need to find a REALLY blue bulb because the ballast will push it whiter anyways. A lot of people say the phoenix 14k is really nice blue on an electronic...

So far I have read the Helios 20k might be a good choice, possibly an XM. I'd like to hear some opinions on 20k bulbs running on m80/hqi ballasts! I'd probably like the look of radiums 20k but unfortunately they don't come in DE.

[mikerobart]

I guess I should mention, bulbs I have tried so far and aren't quite cutting it:

Giesemann Megachrome 20k
Hamilton 14k
Phoenix 14k
Unknown 10k ...

Maybe if someone has an xm20k, helios 20k that is too blue for them, we could swap bulbs!

[mikerobart]

So I just ordered two EVC 20K DE 250W from TB aquatics. Pretty cheap bulbs (only 55 USD) and supposedly decent par for a 20K... I've heard some good things. They are supposed to be more blue in person than the phoenix and retain their blue well even on the M80 magnetic ballast. Here is Sanjay's chart comparing the EVC20k to the Phoenix 14K on the M80:



You can see the PAR of the EVC is less, but the peaks at 450 Nm and 410 Nm are vastly greater than the Phoenix. Also, the EVC is lower in intensity throughout the rest of the spectrum so the blue should be more dominant.

This would likely be too blue for most peoples tastes but I like it quite blue. My sps are all near the top and with the Phoenix I've only had to run MH a few hours a day anyways.. so I'm not too worried about lower PAR, I'll just up the photoperiod, something I've been wanting to do anyways.

The EVC is a cheap bulb that I have heard good things about, so I will let you know what I think once they arrive!