They definitely get it from somewhere else because I remember in 1 of the episodes, they say they need to order thicker acrylic. It might've been the skateboard ramp 1 but I'm not sure
Yeah, Reynolds is top notch. When I was at Dallas World Aq, they did the tunnel for our new bull shark display. They were able to create the largest seamless tunnel in North America for us. It was an amazing thing to see get dropped into place.
I don't think they'd use one brand of cell cast acrylic exclusively. They'd probably go with the brand and type of acrylic that best suits their needs and budget. So the purchasing agent probably shops around for the best price and delivery date. The huge public tanks, probably use the highest quality, most expensive acrylic, like R-Cast. But every job doesn't need the highest quality of acrylic either, like for overflows, sumps, refugiums, and smaller tanks.
If they only need a small quantity in a hurry, they'll probably get it from a local vendor, and pay a premium. If they order by the truck load from a plastics distributor, they'll get a considerable discount. It's a rather competitive market, so there's no reason to be married to one brand of acrylic.