(though I suspect it’s the arm for a 60P rather than the 75P)
I would not be surpriced if both ends of the bended top tube are different lenght to use it above multiple tank models.. 😉
If you can feel the scratches with a finger nail, than polishing is not going to work..
Very nice find is the back glass scratched if not so bad you could turn it round
I believe HS - High pressure sodium or Hl(D) High Intensity Discharge can not be dimmed. Because the extra power peak it needs to start up is given by the ballast, that's why it needs that ballast and cannot be connected directly to the mains.
Thus a dimmer in front of the ballast can not work because you ne underpowering the balast. A dimmer behind the balast wil eliminate the power peak. The light can not switch on..
At least thats what i assume, the balast specs say its for HS and HI(D) lamps, then one of 2 likely is on you hood..
I'm guessing the height of the light can be adjusted in lieu of a dimmer to similar effect.
What you need to look out for is a Dimmable ballast.. 🙂 This is 1-10 volt dim port on the ballast, maybe they come nowadays also with a PWM dimport. But that i do not know.. Automated dimming with 1-10 volt dim port is a bit out of fasion.. I only know of one that ever made an electronic 1-10 volt automated dim puter for dimming Tube ballasts. But he stopt making them when LED and PWM became to popular..
Anyway with a dimmable ballast its possible.. The power peak commes from a capacitor build into the ballast, that only charges and discharges at startup with a high peak, than the balast takes over to feed the lamp. 🙂
Got a Flashback, it was the Flora Mate 1-10 volt Tube light ballast programmable dimmer...No longer in production.. Maybe still to be found as used product on Ebay. It was a mighty popular dimmer back in the 1990's in the vivarium hobby..
Good luck 😉