Tank lid

[starsman20]

I've watched a bunch of videos on making lids out of corrugated polycarb they use for greenhouses. Has anyone used cast acrylic or lexan? I have extra of both for free. Since some tanks are now acrylic it seems that could be used and have better light transmission. Thoughts??

[OceanTruth]

I’ve used them before with success. Only downside is that they start to bow. If it is cut symmetrically you can just flip it over.

[starsman20]

Since I can cnc cut it I wonder if I groove it a bit and glued in another piece to act as a rib for stiffening. Any thoughts on thickness? I have up to 1" and down to 1/8" available for nothing.

[darkG]

I think that will work nicely. I would do it like that even without grooves, if I had to. I would try to use thin material; acrylic actually absorbs water so I doubt thick material will help in the long run - maybe I'm wrong. Several ribs may be better than one.

If you succeed, you may have found yourself a side business 🙂

(Edit: using thick material, I'd like to try an acrylic frame of sorts with a quality soft plastic sheet inserted, if that makes sense. Maybe the flexible sheet part stretched and sandwiched between two, upper and lower, acrylic frame parts... could be slick.) 

Edited March 15, 2021 by darkG

[OceanTruth]

I used 1/4” I believe. I thought it would be thick enough to not bow but it did. The ribbing sounds like a brilliant idea to me. Could probably go much thinner then. 

[gardenman]

I build my own canopies so the fish have jumping room and top them with the thin acrylic used as window glass replacement. Mine don't bow, but they're glued to the canopy so there's no wriggle room for them. I even put my LED lights right against them with no issues. Here's a photo of one with the front door open looking up at the acrylic and light. I use the PVC trim boards for the canopy construction as it's waterproof and never rots. It's also easy to clean should the need arise and it's naturally white so it reflects light on the inside, but also holds paint well so the outside can be easily painted black. I've had this one in use for three or four years now with no bowing. or issues of any sort.

 

[starsman20]

I hadn't thought of doing a canopy but that is a fantastic idea.