Safe paint for sump

[DmitryB]

Soooo the IM sump, and the chamber dedicated for a refugium, has a clear acrylic lid. Who wants their purple light spilling all over the place??? Not me! So what paint is safe to use to paint the lid? I also wish the baffles were not see-through around this chamber, but I guess nothing to be done about that. At the very least I'd like to paint the lid(s). Is Krylon still the paint to go with? The Fusion line?

 

[Matt L]

Should be able to get black acrylic and cut to fit or have someone 3d print a lid.

 

[BryanM]

^^ The above is definitely a good plan.

Krylon Fusion for plastic works, it needs to cure fully before getting anywhere near your sump. 7 days.

 

[UncommonSense]

Here’s an alternative option, a light shade:

Thread 'Barndoor for Kessil H80'

Nov 14, 2025

Can anyone recommend a barndoor for a Kessil H80 refugium light? This would be to go over an in-sump refugium, to limit light spilling over to the skimmer compartment. I looked online but there are so many different barndoors I didn't know how to pick the right one for this light. Thanks!

• RobertK
• Replies: 6
• Forum: Aquarium Lighting

 

[mfinn]

I used a peel and stick black vinyl to cover part of my overflow box. Seems to be holding up fine after 4-5 years.

 

[DmitryB]

Here’s an alternative option, a light shade:

Thread 'Barndoor for Kessil H80'

Nov 14, 2025

Can anyone recommend a barndoor for a Kessil H80 refugium light? This would be to go over an in-sump refugium, to limit light spilling over to the skimmer compartment. I looked online but there are so many different barndoors I didn't know how to pick the right one for this light. Thanks!

• RobertK
• Replies: 6
• Forum: Aquarium Lighting

The light would still bounce out of the refugium, wouldn't it?

 

[DmitryB]

I used a peel and stick black vinyl to cover part of my overflow box. Seems to be holding up fine after 4-5 years.

Same as floor vinyl from Lowe's? Or something more specific?

 

[UncommonSense]

The light would still bounce out of the refugium, wouldn't it?

It does still bounce, but the light intensity has dropped so far by that point that it isn’t going to grow algae like crazy!

 

[exnisstech]

Maybe I'm misunderstanding but don't you want light to shine into the fuge? I don't understand how blacking out the lid is going to allow that or are you using a submersible light?

 

[DmitryB]

Maybe I'm misunderstanding but don't you want light to shine into the fuge? I don't understand how blacking out the lid is going to allow that or are you using a submersible light?

You're right, I'd leave a gap for the light itself, but black out the rest of the lid so there's as little leakage as possible. (Although there's also the option of getting a submersible light.)

 

[exnisstech]

You're right, I'd leave a gap for the light itself, but black out the rest of the lid so there's as little leakage as possible.

Isn't the sump itself clear and will allow light to spill from the sides? Im probably just not understanding because I would just close the stand doors lol.

 

[DmitryB]

It does still bounce, but the light intensity has dropped so far by that point that it isn’t going to grow algae like crazy!

I do want to limit sideways spread so the light isn't growing algae in the next-door chambers. Can vinyl be placed inside the aquarium? So if I try to cover the submersed side baffles with it as well?

 

[chrizo]

I like the barn door idea, I'm gonna 3d print me something like that when mines come in.

 

[DmitryB]

Isn't the sump itself clear and will allow light to spill from the sides? Im probably just not understanding because I would just close the stand doors lol.

The back of the stand is open. The IM sump is actually tinted black; not totally blacked out, but not easy to see either. (Actually so far I've found it mildly annoying because it's hard to see water levels!)

 

[DmitryB]

I like the barn door idea, I'm gonna 3d print me something like that when mines come in.

Barn door?

 

[UncommonSense]

I do want to limit sideways spread so the light isn't growing algae in the next-door chambers. Can vinyl be placed inside the aquarium? So if I try to cover the submersed side baffles with it as well?

I’d be leery about the adhesive used on peel and stick vinyl… I’ve never seen it inside a tank/sump, probably for good reason!

I think getting a thin sheet of ABS, acrylic, etc. in black and cutting it to fit the clear baffles around the refuge would be your best-bet!

(Just note that most plastics swell up appreciably when submerged; up to 3% for cast acrylic, more for extruded! This said, a 18” wide panel of cast acrylic will swell to be nearly 9/16” wider than it was when you cut it, potentially physically tearing the sump apart if it is cut tight to the inside dimensions!

Barn door?

That’s the term used in photo and film for the style of light shade I linked above!

 

[DmitryB]

I’d be leery about the adhesive used on peel and stick vinyl… I’ve never seen it inside a tank/sump, probably for good reason!

I think getting a thin sheet of ABS, acrylic, etc. in black and cutting it to fit the clear baffles around the refuge would be your best-bet!

(Just note that most plastics swell up appreciably when submerged; up to 3% for cast acrylic, more for extruded! This said, a 18” wide panel of cast acrylic will swell to be nearly 9/16” wider than it was when you cut it, potentially physically tearing the sump apart if it is cut tight to the inside dimensions!


That’s the term used in photo and film for the style of light shade I linked above!

This is all great stuff for the side baffles for sure! And good to know about the expansion. I would not enjoy coming home to 80 gallons of water on the floor because the sump got blown up.

Incidentally, I do have a 3D printer. But I haven't even taken it out of the box yet! There's too much going on with the tank set-up. (And I won't be running the refugium right away anyway. When IS a good time to start it?)

 

[UncommonSense]

When IS a good time to start it?)

I’ve had solid luck waiting until there's fish in the tank, but I’m no expert here!