pfo 400 watt ballast and 20k radiums

[Aquattro]

Hmmm, depends who you talk to.... I understand that Osram recomends the M135 ballast for their Radium bulbs. PFO recommends their HQI (Son Agro). They will run on a regular M59 (plain PFO), but will be bluer and may have starting problems down the road. They also run nice on the blueline E- ballast (big bucks).
I have seen them on all of these ballasts, and for me, the Son Agro are the nicest. Again, this is my opinion. You ideally need to see all and make up your own mind.
The M135 is available from Saltwaterconection.com. The PFO HQI is available from J&L, but a dual ballast is $419 +cords. The Son Agros cost me $86 ea. for the bare ballasts, and I screwed them into my existing case. I can get you a source for these if you need one.