How to remove bubbler cover

[MorganJ]

Usually I can find YouTube videos for stuff like this, but I'm coming up empty. I've attached a picture, as you can see this bubbler is broken and collecting a bunch of crud and algae. Awhile back I noticed water was running out of the conduit box, and it turned out there must be a crack in the housing for the light. I've since turned off the water to it, but while I wait to actually fix the thing, I'd like to take the cover off so I can clean it.

I've tried with both a Phillips head and Allen but cant seem to remove whatever is holding it. Is it able to come off easily?

 

[WGpoolnewb]

Is that lens flush with the interior finish? It looks like the lens on my Jandy bubblers, with four holes arranged around the opening. If so, I use this wrench to remove it:

Amazon.com