Safe paint for sump

[mfinn]

I understand the proactive side of trying to limit algae from growing everywhere in the sump, but both my currently running sumps have a refugium area. But algae doesn't really grow anywhere, except on the inside walls of the refugium. I don't have any to speak of. I do get hair algae growing over the baffle coming from the skimmer side. But it just wipes off. I usually only clean it when I harvest the cheato and stir up the refugium.
My biggest issue is algae growing on the inside of the skimmer bodies.
At one time I did have a black plastic film over the outside of the skimmer body, and that helped.