I believe part of your misunderstanding is that fixture is a T5 not a T5HO. (High Output)
They are different fixtures.
Hope this helps. :hippy:

oldmac,

When you overdrive those bulbs with that ballast, is there any adverse effects? Such as lamp life and added heat.

Also do you roughly know total wattage included that ballast?

Figured it would be ok to ask since still on topic.