Type of Plexi

[Pdetevis]

Is it ok to use extruded polycarbonate to make sump?

 

[mcgyvr]

Typically cast acrylic is highly recommended..

see bean/acrylics answer at the bottom
http://www.reefcentral.com/forums/showthread.php?t=1160106

 

[CuzzA]

I talked to many acrylic companies and they all look at me cross eyed when I say cast is better for welding aquariums. Same material just created in two different ways with a similar technique. If I remember correctly it's either melting/mixing acrylic and pouring into a mold, "cast" vs. Melting/mixing acrylic and pushing it through an opening, "extruded". But I've always read cast is better and I'm not an acrylic expert so take that for what it is.

 

[JammyBirch]

Ha I've read the articles too, and built my sump from extruded. There's a bunch of opinions about water absorption and all of that, but you're right the chemistry is the same its the forming that is different.

Do not use poly carb, it does not chemically bond as acrylic does. Poly carb is as strong as steel, chemically as well. You could bolt it together I guess...lol

Use acrylic, and go to a local shop to get machine grade. The stuff from HD/Lowes is not straight and not easy to work with. Be sure to use at least 3/8" thick for the box, baffles and other internal pieces can be 1/4"...

It gets expensive I built my 10g cube sump for $150...

 

[Pdetevis]

i can get this stuff from work, we use it all over. what about using it for baffles only?

 

[CuzzA]

I'm pretty sure you're not supposed to mix different acrylics, but for baffles you'll probably be fine.

 

[sleepydoc]

I'd ask James (acrylics) - like others, I've always read that cast acrylic is better. One guess/possibility is that internal stresses would be different with cast vs extruded acrylic, which may affect the strength of joints. I can also see water absorption being different, but I'm not sure how much that would affect the construction.

I would think that extruded would be fine for baffles. As long as it's the same material (poly methyl methacrylate) it should cement just fine.

 

[thejuggernaut]

I would take what your acrylics wholesaler says with a grain of salt. 99.9% of their business is in the sign/display business. They usually have very little experience with pressure vessels. There are several people on this forum who build pressure vessels on a daily basis and have made all the mistakes for you. Plus, cell cast is expensive, so very few shops stock sizeable quantities of it, so it makes sense they wouldn't try to sell something they don't have. I can say that the generic Arkema (same manufacturer of plexiglass brand) and chemcast have worked fine for me making little projects. With chemcast you can get more colors and is stocked by more companies. Atleast in Houston this holds true. (all of the neon acrylic Synergy Reef uses are made from chemcast). Get cell cast acrylic and you'll sleep better.

 

[sneeyatch]

Polycarbonate absorbs moisture. Even baffles can warp over time. Poly is strong, not strong as steel. If you're building anything that needs or has to have structure to it, use cast acrylic. Extruded works fine for misc things.