Blocking Light in Sump?
 

Our sump is growing a massive amount of algae (and not the good kind). Our skimmer and equipment need constant cleaning.

Would like to block the light from the refigium and the rest of the sump...ideally we would have used black glass for that piece, but too late now.

I originally though of getting a piece of black non translucent acrylic, 1/8 or 1/16 thick. Then I was wondering if there are any other options? Is there anything thinner? I would have to get the acrylic or glass in 3 pieces to fit it in. Has anyone else used anything successfully?

How long is your photoperiod for the refugium lights? How about phosphate levels? The refugium shouldn't be causing the algae problems and I think you should look at other causes before blacking out sump compartments.

I'm inclined to agree, the lamp I have in my sump is a basic Can Tire shop light that isn't exactly spot focused and it bleeds light into the rest of the sump while on (12hrs) and I don't have any appreciable growth of anything other than the macro algae. The clear vinyl tubing has a bit of coralline algae but that's about it. Work on stopping what's feeding the nuisance algae and it'll go a lot further for your tank's health.

what type of bulb?

having the algae in your sump is better then in your Main tank. I would try to block off the skimmer, I would rather clean the skimmer more then pull the crap out of the main display tank.

Go to the craft store and get a sheet of corrugated plastic. Cheap, light weight, and easy to cut.

As Gmgq said a craft store like michaels has mesh knitting mats for .89 a sheet, and you would need some suction cups to hold the mesh down as it will try to float, You can find those cheap at Canadian tire.

Just to clarify,the main tank doesnt have algae, just the refugium. Lights are on 24/7.

Phospates/nitrates/nitrates are always at 0 when tested, and we use phosphate and carbon, which is changed regularly. Fish are fed daily, only what they can eat, frozen brine shrimpw hich is well cleaned. We tried cutting back on feedings, it didn't help. So out of all the causes of algae, it looks like our lighting is the issue (5 t5's mounted to the side of the tank, covering the entire front of the sump)

The algae isn't overwhelming, but having to pull the sump apart every 2-3 months to scrub everything down is getting annoying, and when we reduce the lights to 12 hours our chaeto turns yellow... so preventing the light from going through the refugium into the rest of the sump seems like the best plan.