VHO flicker

[Delphinus]

Put some new VHO actinics in my 75g hood this morning.

One has an awful flicker. I can see little waves dancing back and forth across the tube.

What could cause this? Bad bulb? Bad ballast? Bad wiring? Bad spacing of the sockets?

I don't think it's socket spacing, because they press in on the tubes with a little bit of pressure.

It could very easily be wiring, since everything is DIY. But what should I look for?

The sockets aren't grounded. I'm not sure how to ground the sockets, they're mostly plastic, and they're screwed into wood. Ground the screws maybe? But then do I have to ground EVERY screw???

The reason I swapped out my old tubes was because they weren't lighting all of a sudden. Well they were lighting, but extremely dim. The ends had blackened a bit. They are old bulbs, but I think the blackening is a recent thing.

Heat problems maybe? They do have a fan blowing across them because of the heat from the Iwasaki's.

For now I've just left the VHO's off. Need some ideas what to check for here.. Dang it, I hate fluorescents sometimes! Not quite so cut and dry as other lights.

PS. growing from 110W white tubes, to 110W actinic blue tubes ... what a disappointing sudden lack of intensity. Darn it all, need to shoehorn some more tubes in there now.